Hi kittywink;
First, I want to make sure you understand that you need both an Anti-Virus
(like Nortons AV) and an Anti-Spyware (like Windows Defender) on your
system. Defender alone is not enough to protect you from threats you might
encounter on the internet and must be used alongside an Anti-Virus. That
said it's very possible you could be encountering conflicts between Nortons
and Defender, these have been reported in this newsgroup before. Not all
security products work well together, and particularly more recent releases
of Nortons are known to cause conflicts with Defender.
The other possibility is that you really do want to get rid of Nortons,
maybe to be replaced by another tool. Due to the way that security
products imbed themselves deeply in a system, it's very common that a
simple uninstall through control panel add/remove is not enough to
completely remove all traces of the product. That's also very commonly
encountered with Nortons products, so you might try this removal tool if
that's really where you want to go:
http://service1.symantec.com/SUPPORT/tsgeninfo.nsf/docid/2005033108162039
