Team Explorer SP1 Upgrade Fail

I received an email from a coworker today. She received a new computer and was having trouble viewing work items in Visual Studio. When she tried to open one up, she would receive the following error.

Could not load type 'Microsoft.TeamFoundation.WorkItemTracking.Client.WorkItemTypeDeniedOrNotExistException' from assembly 'Microsoft.TeamFoundation.WorkItemTracking.Client, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.

She had Visual Studio 2008 SP1 installed, and she was obviously connecting to Team Foundation Server. I then decided to look at my version of Team Explorer and compare it to hers. In my installed products (under Visual Studio, Help, About) I had “Microsoft Visual Studio 2008 Team Explorer - ENU Service Pack 1 (KB945140)” and she did not.

The updates to Team Explorer come from Visual Studio 2008 SP1, so my best guess is that her system had SP1 installed before Team Explorer was installed. If you ever encounter this problem, the fix is to reinstall Visual Studio SP1.