I'm having a similar problem with the Max 2010 64bit version. Everytime I apply a vertex paint modifier it crashes. Switched over to the 32bit version and everything works fine. I'm having some performance slowdowns when I hide polygons though, but it's better than the permanent crashes I've got with the 64bit version.
Im on 2010 64bit and usually I can see crashes coming, but this is the only time It doesn't even freeze, and like Xoliul said the first hours of unwrapping went just fine and then once I went back to add some things and re-pack it was poof gone. I should remember to not let my computer automaticly do anything, I'll try and…