After upgrading one of our production environments to Visual Studio Team System 2008 whenever I launched Microsoft Word (or something that uses Microsoft Word such as Microsoft Outlook) the Windows Installer dialog would appear and after some time complain that it could not write to C:\Program Files\Microsoft Visual Studio 9.0\Common7\Tools\vsvars32.bat. Because I’m running Windows Vista I don’t by default have write access to the files under C:\Program Files\ and the installer wasn’t prompting me to escalate my privileges which resulted in the installer failing.
I thought the solution to the problem was to explicitly launch Microsoft Word as administrator once to allow the installation to complete successfully. Unfortunately it appears to be a per-user installation, so what I had to do was temporarily grant the Users group Full Control to C:\Program Files\Microsoft Visual Studio 9.0\Common7\Tools\vsvars32.bat to allow the installation to complete as the current user.
UPDATE: This made the installation succeed but didn’t stop it running every time I launched an Office product.
UPDATE 2: It turns out that this was actually caused by a conflict with the WinZip Email Companion add-in. Disabling this made the problem go away.