I’ve had intermittent editor crashes with Unity 3.0 on my Windows 7 machine (64 bit home premium). It seems that rather than displaying an error for a problem (like adding 2 linerenderers to the same GO) it crashed the editor, and worse yet, corrupted files on my HD. An identical issue under 2.6.1 displays an error message and doesn’t crash the editor. I posted a bug report but UT wasn’t able to reproduce the issue, so I don’t think anythings been done about it and it could still exist in 3.1 (I haven’t attempted to use any version of 3.x since the HD crash issue).