I have had the same problems with Norton/ Symantec and cannot agree more. After the umpteenth reformat due to Norton Internet Security being a load of sh*t, not to mention a SERIOUS drain on my poor laptop's resources, I finally read Karoush Ghazi's Tweaking Comapnion for XP. 186 pages of gold dust
I now use Tiny Firewall (free), AVG Anti Virus (free), Ad Aware (free), Spybot (free) and FireFox (free). I was so impressed that I even donated to all of these people (you don't have to buy their products but if you like it you can donate IF you want to - no pressure).
I have not had a single problem in more than a year and my laptop has never been faster or more stable.
I can only recommend you download the Tweaking Companion for XP from his site, (free download),
www.tweakguides.com and read it from cover to cover.
At the end of the day you don't have to do anything he recommends if you don't want to. (Unlike Symantec who forces the Resources Hog on you!)