Can't open Excel files....please help

When trying to view Excel files I always get the error message: "Your virus scanner has detected a problem with the file… can’t open file."After dumping Norton 2004 (been using avast since then) my Excel files won’t open. I am using Excel viewer 2003. I have scanned them ( right-click then click on scan file with avast) before
opening them but still get the same message. Any suggestions to remedy this???

 Thanks in advance for your help.

That doesn’t seem to be an avast virus alert format ?
Or is it a error text, if you can post a screenshot that might help ?

How did you get rid of NAV as it is harder to get rid of than some virus infections ?

A link worth looking at, which is a program removal tool that can remove the remnants of a number of different Norton Programs:
Removing your Norton program using SymNRT
You can also download SymNRT, a Norton uninstall tool that uninstalls all Norton 2004/2005/2006 products.