Problem between Norton Internet Security and Windows Update

Hello,

 

I think I'm having a problem with Norton Internet Security.

A while ago, I was on the Internet, on a newspaper site, and I noticed that the Java icon appeared on the multitask bar, on the downright corner of the monitor. Nothing unusual, I thought. Then a window from NIS pops out and says that the file windowsupdate.exe had a suspicious behaviour, and so it removed that file, as well as the ctsvmapi.dll (I think it's a system file because it's on c:/windows\system32). I thought it was strange because I've never had any problems or clashes between NIS and Windows Update. Because I didn´t want to be without Windows Update, I went on to investigate and try to access Windows Update site. When I entered the site, I had to install the file windowsupdate. Everything went well. Then, a view moments later, NIS said that the file msconfig.exe was having a suspicious behaviour and removed it and the ctsvmapi.dll again.
What's wrong? Can you help me? I don't  want to loose Windows Update or any system file.
My operating system is Windows XP Media Center Edition Service Pack 3. My NIS version is the 2012.