After 10 yrs as a die hard Norton customer I finally made a switch to another vendor due to unending conflicts with Norton 360. Spent many hours with tech support on a couple of different occasions, but to no avail. Just couldn't spend any more time trying to chase out the gremlins. Made the switch and have not had ONE issue. FWIW. 
I was a loyal customer and cheerleader for Norton products since '95, but after my last three attempts to upgrade their programs (Antivirus, Internet Security, System Works, etc.) I've decided the aggravation is not worth it. IMHO, most Norton products tie up too many system resources, slow your computer excessively, and create
conflicts not only with other software but also with previous versions of their own stuff! Even better, many of the utilities in System Works haven't been updated since Win 95, and some no longer work at all with the latest versions of XP/Internet Explorer or Vista (they conveniently don't mention this on the outside of the box or in the product description). And to top it all off, their so-called tech support is the worst I've ever experienced with any computer product.
I've had to format my C: drive in the past and reinstall all my software due to Norton upgrade issues (I'm now a little smarter, I only load new software after making a new Ghost backup image of the C: drive). Most recently I attempted to update to Internet Security 2007 and found the same issues that caused problems on previous upgrade attempts over the past few years. After attempting all the "fixes" Symantec lists on their web site, I wound up using the Ghost image to revert back to the older version and just bought another one year update subscription for now. The 2007 version is collecting dust in the closet; another $50 wasted. I now consider Norton to be in the same category as H-D; neither should hold their breath while waiting for me to spend any more money on their poorly designed and executed products.
Jerry