IF you are very knowlegeable with the Registry and its aspect for permissions, I would delve deeply into it. Otherwise don't consider playing in it, unless you are willing to format in the not - too - distant future!!! You may need to run "sfc /scannow" while in Windows (have your Windows media in the drive). With these issues and if you're on DSL, etc., unplug before you uninstall the Symantec program, repair it, etc.
Have you run rootkit, anti-spyware scans or backed up the registry before the install? All advanced/expert users will inform you to, once in a while do a complete re-install > there's nothing better than a deep "housekeeping".
And to my original reply .... 10.1.x.xxxx does work with XP. I may have presumed a Vista issue was at hand.
HTH