我的工作项目在TFS中消失了

We use VS2008 with TFS for source control at my workplace and it works fine, however today we experienced a problem when trying to associate our pending changes with a work item. Usually when I want to associate changes with a work item I just go to the second tab from the top in the "pending changes" window, check the work item that fits the changes and check in. Today however, all my work items were gone from the list. I can select a suitable query from the drop down box and this works fine, so the projects are there.We use VS2008 with TFS for source control at my