When I start the newly-downloaded 124.524, I get the following:
"Plugin com.intellij failed to initialize and will be disabled:
Illegal constant pool index 46080 for method signature in class file com/intellij/util/xml/ui/DomCollectionControl
Please restart JetBrains RubyMine
The dialog does not actually allow me to click OK and I have to force-quit.
OS X Mountain Lion. This system was happily running the previous build of EAP, so this is a new issue.