I wanted to increase the GoogleRank for Aaron's article:
http://blogs.msdn.com/astebner/archive/2005/12/16/504906.aspx

My machine's Visual Studio 2005 installation has been partially hosed since somewhere around Beta2. Various tasks would regularly fail with "Package Load Failure" error messages. I could compile and perform basic functions with it, but was forced to use cmd-line for a lot of stuff. Like editing project files. This was caused by the multiple betas, CTPs, and hand-built CLRs that I've had installed over the past year; it seems some cruft had built up inside of the native-cache.

I followed his steps, and now it works like a charm. Sweet.