Today, after installing the RTM version of VS.NET 2005, I got some errors due to previous installs of the Betas. One of the was a Package Load Failure for the Class Designer. After a quick search on MSDN Product Feedback Center I found a case (FDBK39168, now closed) with a really nice tool that scans and fixes a number of known issues in Visual Studio.NET. You can download it here: http://astebner.sts.winisp.net/Tools/ttool.zip if you have the same or similar errors.