|If you can log into safe mode, I would recommend to a system restore to before Norton was installed (or at least the updates) if possible.|
Or: Insert XP install or restore disk, boot to that and begin the system restore from there.
Or: contact Norton Support....They caused it.
Personal Opinion: If they are not helpful, and you have to reload windows, dump them and replace with something better. For antivirus/antispyware, I use Webroot's Antivirus with Spysweeper, and have for years - I'm a reformed Norton user myself. Use a good lean product and keep your computer clean of junk and you will probably pick up a lot of speed over Norton Bloatware.