Problem with Layers

Hi, I’m having some trouble with a scene i’ve been working on. Everytime I try to switch to the main layer, Blender crashes. I’ve tried the same with 2.67, 2.66, 2.63, and 2.49. The only one that worked was 2.49 ( which is useless to me right now), so I don’t think it has much to do with my computer. What could be causing the problema?
Thanks a lot!

Open in 2.49, remove something, save, open in blender 2.68, does it open Yes/No. If yes, great, if no, go back to the beginning

Remove something like… let’s say, a lamp?