Happened to me too.

I think the reason for this is that the Lucky Charm artifact fails to serialize, and so if that has been generated by the time you save, it will fail to save correctly.

It also happened to me, but later broken save file suddenly loaded.
@Telrunya:
Why do you think that it was caused exactly because of Lucky Charm? Just curious, where could I miss some information...

I get the same thing with the following in the c:\Users\<username>\.jade\log\jade.log file after the crash:
2011-07-03 12:34:45,724 ERROR Thread-13 de.adom.jade.utils.ErrorUtils - Handling error.
java.io.EOFException: Unexpected end of ZLIB input stream
at java.util.zip.InflaterInputStream.fill(Unknown Source)
at java.util.zip.InflaterInputStream.read(Unknown Source)
at java.util.zip.GZIPInputStream.read(Unknown Source)
at java.util.zip.CheckedInputStream.read(Unknown Source)
at java.io.ObjectInputStream$PeekInputStream.read(Unknown Source)
at java.io.ObjectInputStream$PeekInputStream.readFully(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.readInt(Unknown Source)
at java.io.ObjectInputStream.readHandle(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at java.util.HashMap.readObject(Unknown Source)
at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeReadObject(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at de.adom.jade.kernel.storage.ObjectSerializationGamePersistenceHandler.loadImpl(SourceFile:123)
at de.adom.jade.kernel.storage.AbstractFileBasedGamePersistenceHandler.load(SourceFile:115)
at de.adom.jade.kernel.game.startup.loader.steps.RestoreGameStep.execute(SourceFile:49)
at de.adom.jade.kernel.game.startup.loader.StartupSequence.execute(SourceFile:99)
at de.adom.jade.kernel.game.startup.loader.JadeLoader$1.runImpl(SourceFile:71)
at de.adom.jade.utils.VerboseRunnable.run(SourceFile:35)
at java.lang.Thread.run(Unknown Source)
2011-07-03 12:34:45,728 ERROR AWT-EventQueue-0 de.adom.jade.utils.ErrorUtils - *** An internal error has occurred while another error was processed.
2011-07-03 12:34:45,729 ERROR AWT-EventQueue-0 de.adom.jade.utils.ErrorUtils - The following exception occurred:
java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(Unknown Source)
at de.adom.jade.ui.basic.ErrorDialog.<init>(SourceFile:80)
at de.adom.jade.ui.basic.DefaultUserInterface$1.runImpl(SourceFile:153)
at de.adom.jade.utils.VerboseRunnable.run(SourceFile:35)
at de.adom.jade.ui.basic.DefaultUserInterface.displayErrorDialog(SourceFile:159)
at de.adom.jade.utils.ErrorUtils$1.runImpl(SourceFile:127)
at de.adom.jade.utils.VerboseRunnable.run(SourceFile:35)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Edit:
I got the exact error message as below during the save in my log.

The same thing has happened to me a couple times, and looking at JADE's log file after saving, I found this:
java.io.NotSerializableException: de.adom.jade.items.list.LuckyCharmOfGygaz$GaryGygaxMemorialDay
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at java.util.HashMap.writeObject(Unknown Source)
at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at de.adom.jade.kernel.storage.ObjectSerializationGamePersistenceHandler.saveImpl(SourceFile:75)
at de.adom.jade.kernel.storage.AbstractFileBasedGamePersistenceHandler.save(SourceFile:58)
at de.adom.jade.kernel.game.Game.save(SourceFile:671)
at de.adom.jade.ui.commands.CommandSave.executeMetaCommand(SourceFile:54)
at de.adom.jade.ui.commands.MetaCommand.executeImpl(SourceFile:54)
at de.adom.jade.ui.commands.Command.execute(SourceFile:350)
at de.adom.jade.beings.brains.PCBrain.doActImpl(SourceFile:92)
at de.adom.jade.beings.brains.AbstractBrain.doAct(SourceFile:320)
at de.adom.jade.beings.Being.actImpl(SourceFile:505)
at de.adom.jade.kernel.actors.AbstractActor.act(SourceFile:53)
at de.adom.jade.kernel.actors.ActorReference.act(SourceFile:58)
at de.adom.jade.kernel.GameLoop.run(SourceFile:86)

Attempting to load the save game gives the same kind of error as above. Although, it could be the case that there is more than one reason for failing to load...

Forgot java.io.Serializable with that. Damn.

@Telrunya & Pustka: Please provide me your real names for the credits section :-) Your hints were on target! Thanks to all others! (E-Mail me at creator(at)ancientdomainsofmystery.com). Thanks!