It could be the registry in Win XP has become corrupted. Which means it would be necessary to do a complete reinstall of Win XP. However, you should try the following before doing so...
1. Defrag your hard drive.
2. Download a program called CCleaner which can be used cleanup invalid registry keys.
3. Do a Windows XP repair. Read the instructions that came with your laptop to find out what the steps are to do that. It will be the same initial steps for a complete re-install of Windows XP (which means your hard drive will be formated), but is a different option and will not delete any data on your hard drive.