Abby, it may have been that e-mail, or it may have been some other one and it just showed up when you tried to run the .exe file. That may be why the attachment looked OK to the anti-virus program. There's a possibility you may have the virus on your system someplace and should scan the whole thing. Of course, I'm paranoid when it comes to viruses, and I don't necessarily know what I'm talking about.

Sounds like the virus installs itself and tries to run whenever you try to open an exe file. Since it screwed up the name of it's own winsvrc.exe file (it's installed as winsvrc.vbs) it can't the file.

There is information on Navidad, and how to get rid of it here at F-Secure.