On my machine, While TFS (Team Foundation Server) items are being accessed (in the sense, clicking on any work item to view it's details), The VS 2008 Team Explorer is showing the below 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'.
Seems that the order of the installation that I did was wrong - Installed VS 2008 SP1 before Team Explorer and should actually be other way round. Re-installing the VS 2008 SP1 in such cases, shall resolve the issue.
Order of installation must always be - Visual Studio 2008 > Team Explorer > Visual Studio 2008 SP1.