Installed the latest QuickTime recently as required for WebEx, then today I could not start a new WebLogic domain. To save you all the searching I went through, it turns out that the QuickTime adds .;C:Program Files (x86)Javajre6libextQTJava.zip to the classpath, which causes the following error starting WLS:
QTJava.zip was unexpected at this time
Remove the classpath entry and the QTJAVA entry from your environment variables if you have the same issue. If you are starting WebLogic from a console you will need a new console session. If from an IDE, you will need to restart the IDE afterwards for the update to take effect.