text file icons have changed

I have Norton 2009 AV and Internet Security.

 

I left my computer running overnight. When I got up today, all my text file icons on my desktop and in Windows Explorer had changed to the Norton icon. The text in the files were unchanged. I ran an update and full scan, and no problems were reported.

 

I did the online chat thing with Norton, and the tech assured me that this is normal, which I thought was laughable. He said it was normal after a full scan because Norton marks the files it has checked, but I've run many scans before, and only text file icons were changed.

 

So.... if this is normal, are everyone's text file icons being replaced by the Norton icon?

 

My thought is that a virus writer is trying to demonstrate that he can defeat Norton protection.

 

Thanks for any help on this.