If you suspect Norton make sure all elements of Norton are turned off and not allowed to start up on boot. If the problem still occurs Then it's niot Norton.

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My old version of photoshop has a conflict with Wings on my ME computer so that if I use Wings I have to reboot before photoshop will work. In the past Norton has been notorious for conflicting with other applications so I wouldn't doubt that Norton is a likely suspect.   Same with photoshop. My XP computer doesn't seem to have any conflicts but then I'm not using Norton on it. 

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Check to see that the system restore is enabled and at least 10 percent of your main drive (C:) is free.(there is also something about how much hard disk space to use for system restore ) You might also have turned off one or more essential services. Never mess with the services settings unless you understand what they do.

if you have the disk for xp a nondestructive repair is possible but if your xp came loaded  with the computer you willl revert to the way it was when you got the computer. all your apps will still be there but the registry entrys will be gone, all the JUNK that came with the computer will be
re-installed and you will spend weeks getting everything straightened out.