I googled MSVCR80.dll .
I came up with this link, which you should read and try to understand thoroughly:
http://www.instant-registry-fixes.or...issing-errors/
In my own interpretation of your issue:
MSVCR80.dll is a file in the C:\System32 folder that some applications need.
From your explanation, apparantly, Pro Tools requires it. There are different versions of MSVCR80.dll . If a program needs it, then, it installs MSVCR80.dll when that program gets installed. In other word, reinstalling Pro Tools should reinstall the correct version of MSVCR80.dll . If the problem is a corrupted MSVCR80.dll file in the C:\System32 folder, you could just download a copy of that file and put it in the folder. But that could cause version conflict issues. It is best if you let the software reinstall it. Installing other programs could also take care of the reinstallation of MSVCR80.dll . .NET Framework 2.0 is a program that uses this file.