You could try changing the mode of the present install: http://www.sevenforums.com/tutorials/316-compatibility-mode.html then trying the repair again.To repair the product on Windows Vista
- Click Start, click Control Panel, and then click Programs.
- Click Programs and Features and then select the Visual Studio Edition you installed.
- Click Uninstall/Change.
- In the setup wizard, select Repair or Reinstall and then click Next.
- Follow the remaining instructions in the installation wizard to finish.
Source: How to: Repair Visual Studio