Has anyone else had a problem with new toolbox tabs not persisting from one session of VS.Net to another?

I add a "mmWinForm Controls" tab to the toolbox and add items from the WinForms dll and the controls show up properly in the tab. I can use them and they work fine. I close the VS.Net session for the day. When I re-open my VS.Net solution, my newly added tabs are no longer there. Using "Show All Tabs" brings no joy. I gnash my teeth and re-configure the Toolbox tabs, again.

Thanks for any help with this issue,
Jim