I have an older Windows 2000 Professional system that about a month or so ago started getting messages from ClamAV that MSVCR80.DLL was missing in the WINNT/system32 directory. My investigation found that ClamAV has moved it to the quarantine folder. I ran an update of ClamAV in case I did not have the updates, and did a search on MSVCR80.DLL and found slightly newer versions of the file in the WINNT/winsxs directory and copied that one into the system32 folder, then rebooted and ran new hard drive and memory scans. All is fine now.

I understand ClamAV corrected a false positive that may have quarantined this DLL recently.

Just posting this solution to help others. I think either this was a false-positive or possibly there was a version of the DLL that was infected. The version of MSVCR80.DLL that was flagged is from Microsoft Visual Studio 2005 version 8.0.50727.762

8.0.50727.91 works just fine.

Hope that helps.