There are no machine details which means I would guess badly. Are you seeing those words in red?
For now, try this and that.
This -> http://forums.cnet.com/5208-6132_102-0.html?messageID=3290594&tag=forums06;posts#3290594
That -> http://reviews.cnet.com/4520-11319_7-6240575-1.html
And finally consider that repairing this OS is not always possible. Even more so with so few details. I'm beginning to think that in such cases it is best to wipe the machine and start fresh.
I'm running XP Home Edition and when I click Start/All Programs and try to open Accessories, it usually stops at Dell Accessories and then hangs. I can only restart by powering off. I've tried safe mode, but that doesn't help either. Hope someone can help me solve this irritating problem!