"Launch4j"
An error occurred while starting the application
Had same problem on a Win7/32bit and winXP, spent some time to figure out why.
I have an Hardware folder in my documents/arduino path that cause crash, remove it fix it. It's obviously a bug of the release 1.5.1r2 since 1.5 not have this problem and hope will be fixed soon since many users use the hardware folder to access unsupported cpu's. I didn't find the infos easily so I'm write here (even if was mentioned in this discussion just before).