I was reading VS2008 SP1 known issues file and this issue struck me:
2.1.4 Visual Studio 2008 SP1 installation fails when the Windows Vista sidebar is enabled.
Visual Studio 2008 SP1 installation fails when the Windows Vista sidebar is on.
To resolve this issue:
1. Right-click the Sidebar icon in the notification area, at the far right of the taskbar.
2. Click “Exit”.
How can Vista sidebar interfere with VS2008 SP1 installation? This has to be the most peculiar installation issue I have seen in a while. Well, it didn’t complain when I installed the SP1.