Not sure how much information this gives you but I think I understand the circumstances that caused it.

I had an unidentified cloak of elvenkind equipped. I walked through a shop that stocked the same item so it became partially identified as "cloak of elvenkind" in my inventory. I took it off and put it back on while still in the shop. I noticed that when I tried to do so, the dialogue at the top of the screen displayed the full name of the cloak "silk cloak of elvenkind {Ap+2} of precision (+3, +0) [+1, +0]" rather than the basic "clock of elvenkind" as it had been identified. I'm guessing this occured because I was standing in the shop. At that point the error was generated and the cloak did not equip. Subsequently I was unable to equip any cloak for the life of that character as I would always receive this error.



A controlled JADE error occurred.
Please see the stack trace for details.

de.adom.jade.JadeError: Failed to remove item 'de.adom.jade.items.list.cloaks.CloakOfElvenkind@175eddc/silk cloak of elvenkind {Ap+2} of precision (+3, +0) [+1, +0]' from the item list 'de.adom.jade.items.MutableItemList@19cceab' because it could not be found.
at de.adom.jade.items.MutableItemList.remove(SourceFile:254)
at de.adom.jade.items.Inventory.removeFromStuff(SourceFile:468)
at de.adom.jade.beings.brains.actions.list.EquipItemAction.finishAction(SourceFile:85)
at de.adom.jade.beings.brains.actions.AbstractExtendedAction.continueExecuting(SourceFile:149)
at de.adom.jade.beings.brains.AbstractBrain.doAct(SourceFile:375)
at de.adom.jade.beings.Being.actImpl(SourceFile:674)
at de.adom.jade.kernel.actors.AbstractActor.act(SourceFile:58)
at de.adom.jade.kernel.actors.ActorReference.act(SourceFile:60)
at de.adom.jade.kernel.GameLoop.run(SourceFile:111)

--- System information: ---

jnlpx.remove: 'false'
file.encoding.pkg: 'sun.io'
java.home: 'C:\Program Files\Java\jre6'
deployment.security.askgrantdialog.notinca: 'true'
deployment.repository.askdownloaddialog.show: 'true'
deployment.system.security.trusted.jssecerts: 'C:\\Program Files\\Java\\jre6\\lib\security\trusted.jssecerts'
deployment.console.startup.mode: 'HIDE'
java.endorsed.dirs: 'C:\Program Files\Java\jre6\lib\endorsed'
deployment.security.sandbox.jnlp.enhanced: 'true'
deployment.system.security.blacklist: 'C:\\Program Files\\Java\\jre6\\lib\security\blacklist'
deployment.javaws.concurrentDownloads: '4'
deployment.security.sandbox.awtwarningwindow: 'true'
sun.os.patch.level: 'Service Pack 1'
java.vendor.url: 'http://java.sun.com/'
deployment.security.blacklist.check: 'true'
deployment.user.security.trusted.jssecacerts: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.jssecacerts'
deployment.javaws.home.jnlp.url: 'http://java.sun.com/products/javawebstart'
java.version: '1.6.0_29'
deployment.javapi.trace.filename: ''
deployment.max.output.file.size: '10'
java.vendor.url.bug: 'http://java.sun.com/cgi-bin/bugreport.cgi'
deployment.user.security.trusted.cacerts: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.cacerts'
java.protocol.handler.pkgs: 'com.sun.javaws.net.protocol|com.sun.deploy.net.protocol'
javaplugin.proxy.config.type: 'direct'
deployment.user.tmp: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\tmp'
user.name: 'Nomad'
deployment.user.logdir: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\log'
sun.io.unicode.encoding: 'UnicodeLittle'
deployment.browser.path: 'C:\Users\Nomad\AppData\Local\Google\Chrome\Application\chrome.exe'
deployment.cache.max.size: '-1'
sun.jnu.encoding: 'Cp1252'
java.runtime.name: 'Java(TM) SE Runtime Environment'
jnlpx.home: 'C:\\Program Files\\Java\\jre6\\bin'
deployment.system.security.trusted.publishers: 'C:\\Program Files\\Java\\jre6\\lib\security\trusted.publishers'
java.specification.name: 'Java Platform API Specification'
deployment.security.mixcode: 'ENABLE'
user.timezone: 'Europe/London'
deployment.browser.vm.mozilla: 'true'
deployment.security.SSLv3: 'true'
deployment.proxy.override.hosts: ''
path.separator: ';'
deployment.javaws.installURL: 'http://java.sun.com/products/autodl/j2se'
deployment.javaws.ssv.enabled: 'true'
jnlpx.heapsize: 'NULL,768m'
file.encoding: 'Cp1252'
deployment.user.security.trusted.publishers: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.publishers'
sun.java.command: 'com.sun.javaws.Main C:\Users\Nomad\AppData\Local\Temp\javaws2'
deployment.javapi.log.filename: ''
deployment.user.cachedir: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\cache'
deployment.javaws.cache.update: 'false'
deployment.security.validation.crl: 'false'
java.io.tmpdir: 'C:\Users\Nomad\AppData\Local\Temp\'
deployment.version: '6.0'
sun.awt.warmup: 'true'
user.language: 'en'
line.separator: '
'
deployment.system.tray.icon: 'true'
deployment.user.security.policy: 'file:/C:/Users/Nomad/AppData/LocalLow/Sun/Java/Deployment/security/java.policy'
jnlpx.jvm: 'C:\\Program Files\\Java\\jre6\\bin\\javaw.exe'
java.vm.info: 'mixed mode'
sun.desktop: 'windows'
java.vm.specification.name: 'Java Virtual Machine Specification'
deployment.max.output.files: '5'
deployment.update.mime.types: 'true'
deployment.security.browser.keystore.use: 'true'
deployment.security.jsse.hostmismatch.warning: 'true'
deployment.system.security.cacerts: 'C:\\Program Files\\Java\\jre6\\lib\security\cacerts'
deployment.proxy.type: '3'
deployment.user.security.trusted.jssecerts: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.jssecerts'
jnlp.versionEnabled: 'true'
deployment.security.password.cache: 'true'
deployment.javaws.shortcut: 'ASK_IF_HINTED'
java.awt.printerjob: 'sun.awt.windows.WPrinterJob'
deployment.security.https.warning.show: 'false'
deployment.javaws.autodownload: 'ALWAYS'
deployment.proxy.bypass.local: 'false'
http.auth.serializeRequests: 'true'
deployment.javaws.logFileName: ''
os.name: 'Windows 7'
java.specification.vendor: 'Sun Microsystems Inc.'
deployment.javaws.uninstall.shortcut: 'false'
deployment.system.security.jssecacerts: 'C:\\Program Files\\Java\\jre6\\lib\security\jssecacerts'
deployment.system.security.oldcacerts: 'C:\Program Files\Java\jre6\lib\security\cacerts'
java.vm.name: 'Java HotSpot(TM) Client VM'
java.quick.starter: 'false'
deployment.security.askgrantdialog.show: 'true'
java.library.path: 'C:\Program Files\Java\jre6\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\Program Files\Java\jre6\bin;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\Wind owsPowerShell\v1.0\;"C:\Program Files\Java\jre6\bin";.'
java.class.version: '50.0'
deployment.control.panel.log: 'false'
deployment.system.security.trusted.clientauthcerts: 'C:\\Program Files\\Java\\jre6\\lib\security\trusted.clientcerts'
deployment.trace: 'false'
deployment.security.clientauth.keystore.auto: 'true'
deployment.security.validation.ocsp: 'false'
deployment.javapi.cache.update: 'true'
deployment.browser.vm.iexplorer: 'true'
deployment.cache.jarcompression: '0'
deployment.system.security.trusted.libraries: 'C:\\Program Files\\Java\\jre6\\lib\security\trusted.libraries'
deployment.security.validation.ocsp.publisher: 'false'
deployment.javaws.update.timeout: '1500'
sun.boot.library.path: 'C:\Program Files\Java\jre6\bin'
sun.management.compiler: 'HotSpot Client Compiler'
java.awt.graphicsenv: 'sun.awt.Win32GraphicsEnvironment'
deployment.user.extdir: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\ext'
user.variant: ''
deployment.system.security.trusted.certs: 'C:\\Program Files\\Java\\jre6\\lib\security\trusted.certs'
deployment.system.security.oldjssecacerts: 'C:\Program Files\Java\jre6\lib\security\jssecacerts'
deployment.proxy.same: 'false'
deployment.security.authenticator: 'true'
deployment.javaws.traceFileName: ''
deployment.user.security.trusted.clientauthcerts: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.clientcerts'
java.vm.specification.version: '1.0'
deployment.user.security.blacklist: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\blacklist'
deployment.system.cachedir: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\SystemCache'
awt.toolkit: 'sun.awt.windows.WToolkit'
sun.cpu.isalist: 'pentium_pro+mmx pentium_pro pentium+mmx pentium i486 i386 i86'
java.ext.dirs: 'C:\Program Files\Java\jre6\lib\ext;C:\Windows\Sun\Java\lib\ext'
os.version: '6.1'
user.home: 'C:\Users\Nomad'
deployment.user.security.trusted.certs: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.certs'
trustProxy: 'true'
java.vm.vendor: 'Sun Microsystems Inc.'
deployment.javapi.lifecycle.exception: 'false'
user.dir: 'Z:\Downloads'
deployment.cache.enabled: 'true'
sun.cpu.endian: 'little'
jnlpx.splashport: '53340'
deployment.security.notinca.warning: 'true'
deployment.javaws.splash.index: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\splash\splash.xml'
jnlpx.vmargs: '-Djnlp.versionEnabled=true'
java.vm.version: '20.4-b02'
deployment.security.trusted.policy: ''
java.class.path: 'C:\\Program Files\\Java\\jre6\\lib\\deploy.jar'
os.arch: 'x86'
deployment.javapi.stop.timeout: '200'
deployment.mime.types.use.default: 'true'
deployment.security.pretrust.list: 'true'
java.rmi.server.RMIClassLoaderSpi: 'com.sun.jnlp.JNLPRMIClassLoaderSpi'
deployment.capture.mime.types: 'false'
jnlpx.origFilenameArg: 'Z:\Downloads\jade.jnlp'
javawebstart.version: 'javaws-1.6.0_29'
deployment.security.TLSv1: 'true'
sun.java.launcher: 'SUN_STANDARD'
deployment.jpi.mode.new: 'true'
deployment.javaws.muffin.max: '256'
deployment.log: 'false'
https.protocols: 'TLSv1,SSLv3'
java.vm.specification.vendor: 'Sun Microsystems Inc.'
file.separator: '\'
java.runtime.version: '1.6.0_29-b11'
sun.boot.class.path: 'C:\Program Files\Java\jre6\lib\resources.jar;C:\Program Files\Java\jre6\lib\rt.jar;C:\Program Files\Java\jre6\lib\sunrsasign.jar;C:\Program Files\Java\jre6\lib\jsse.jar;C:\Program Files\Java\jre6\lib\jce.jar;C:\Program Files\Java\jre6\lib\charsets.jar;C:\Program Files\Java\jre6\lib\modules\jdk.boot.jar;C:\Program Files\Java\jre6\classes;C:\\Program Files\\Java\\jre6\\lib\\javaws.jar;C:\\Program Files\\Java\\jre6\\lib\\deploy.jar;C:\\Program Files\\Java\\jre6\\lib\\plugin.jar'
java.security.policy: 'file:C:\\Program Files\\Java\\jre6\\lib\\security\\javaws.policy'
deployment.user.security.trusted.libraries: 'C:\Users\Nomad\AppData\LocalLow\Sun\Java\Deployment\security\trusted.libraries'
user.country: 'GB'
deployment.security.expired.warning: 'true'
deployment.repository.enabled: 'true'
deployment.security.SSLv2Hello: 'false'
deployment.javapi.runtime.type: '0'
deployment.javaws.associations: 'ASK_USER'
java.vendor: 'Sun Microsystems Inc.'
java.specification.version: '1.6'
deployment.user.security.saved.credentials: '...