Today I got all sorts of “SideBySide” errors
“Generate Activation Context failed for C:\Program Files\ESET\ESET NOD32 Antivirus\MFC80U.DL” etc and
“The manifest file contains one or more syntax errors.”

This seems to be due to a Windows update that was pushed out back in July, this was for the VS2005 CRT and modified developers environments without telling them.
You can read more about it here:

I had to manually apply this update to resolve it.