VS10 doesn't work in 64-bit systems
Visual Studio 2010 "Ultimate" just doesn't work on 64-bit systems. Here's the bug: https://connect.microsoft.com/VisualStudio/feedback/details/510008/cannot-open-files?wa=wsignin1.0#tabs
You have to run it in Compatibility Mode for XP Service Pack 3.
The bug was found during the Beta almost two years ago and it's still not fixed. Pathetic.