I received this information when decrypting Skyrim on Steam. No, Steam forums have been down since November 6th so can't go there.

The object C:/programfiles (x86)\steam\steamapps\common\sk....\skyrimlauncher.exe

Threat probably unknown crypt.win32.virus

comment Event occured on a file modified by the application c:\programfiles (x86)\steam\steam.exe

Why is this happening? I highly doubt there's a virus in the program from Steam. Has anyone ever seen this happen? Should I delete, no action? What?

Most likely a false positive. Ignore it for now. Don't delete the file.