'w'alk command and babbling mouth.
The effect of corruption "You sport a babbling mouth on your forehead that rants and raves dark secrets." occasionally has the PC cast a random spell.
If the 'w'alk command is issues and this effect of corruption causes the PC to cast a spell the execution of the command continues after the spell is cast.
I can think of a few situation where this behaviour could result in an unfair outcome.
I suggest that the PC stops walking when this effect of corruption causes the PC to cast a spell.