Open the attached file. Apply the Mirror modifier. Blender crashes immediately.
It has something to do with vertex groups. When I remove all groups, the crash doesn't happen.
I tried to reproduce it with Suzanne (with vertex groups including .R .L groups), but then it didn't crash, so I'm not sure what causes it.
Blender svn r41295M
OpenSuse 11.4, Gnome 2.32.1