What are you doing before it crashes? If you're dealing with anything related to lighting, that could be why. It really doesn't like you messing with the light editor.
If you want to see what the shadows look like, using Filtered Relight works better, you shouldn't have to use the Full Relight until you're done with your map....
Well relighting uses your gfx card a lot, it could be integrated video and not able to handle it.. there are actually some variables to lower the fidelity of the relight that might let you finish. For the life of me I can not find it right now though. It's not part of our current prefs.