Executable file got through network

I have Norton Antivirus loaded on my PC (Operating System is Vista)

On Thursday, January 13, 2011 at 9:20pm Norton advised me that I allowed an exe file (rvaddcdusbs.exe) to access my network resources. Since then every single time I click or type anything, a pop up comes up for anti-virus software alert and will not let me go any further (FYI:  I am typing this from another PC)

How do I get rid of it?

Please advise.  Thanks in advance.