Java Platform SE binary Has Stopped Working

I have working / downloading file to my Yun for a few days now and suddenly I'm getting the error message above (and IDE crashes/closes) every-time I try to download a new sketch.

OS: Windows 7 IDE: 1.5.4 Java: Java 7 update 40

I still can download wirelessly but I lose the very helpful/practical Serial debugging functionality.

Any hints? Thanks