Package 'Microsoft.VisualStudio.Xaml' has failed to load properly

I just wanted to give you a heads up, in case you experience the same problem I faced yesterday. After installing the Windows Phone 7 developer tools Visual Studio 2008 suddenly started giving me “Package Load Failure” errors when opening one of my WPF projects.

Here’s what the error message looks like:

Package Load Failure
Package 'Microsoft.VisualStudio.Xaml' has failed to load properly ( GUID = {E58C2A8B-BCC4-4559-AD59-D62EB6D58A22} ). Please contact package vendor for assistance. Application restart is recommended, due to possible environment corruption. Would you like to disable loading this package in the future? You may use 'devenv /resetskippkgs' to re-enable package loading.

The problem is related to the order in which you install the Express SKU and the Standard SKU, which can leave the system in a broken state.

To fix this problem you can run the standalone Visual Studio 2008 Service Pack 1 installer.