什么是我的VS 2008工具箱上的标签＃13119？

I only noticed this last night, as I have not used the toolbox on this particular project for some time. Suddenly, all my Telerik controls, previously on their own tab, were missing, and this mysterious, empty tab #13119 was there. I added a new tab for Telerik and added all the controls, but the Telerik tab remained invisible, although the controls are still ticked to indicate that they are in the toolbox.I only noticed this last night, as I have not u