Media Center window has disappeared

I have been happily watching TV on a relatively small window in Vista 32 SP2 while working on other operations on the rest of the screen - until a couple of days ago when my graphics display crashed (probably due to overloading!).
Since then, I can open Media Center as usual in full screen, but when I try to reduce the window size, it disappears completely (although the sound remains). If I hover over the task bar icon, the picture appears in thumbnail form; if I then try to restore, I get a black screen for a lengthy period - often only cured by Task Manager and End Process - and/or rebooting.
I can't see how to repair the Media Center program - but I note that there is an appropriately dated file called 'ehshell.crash' - shown below:


Unhandled Exception - 04/14/2010 02:01:44
Message: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Exception:
System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
at Microsoft.MediaCenter.Interop.Win32Api.DispatchMessage(MSG& msg)
at Microsoft.MediaCenter.UI.Dispatcher.DispatchNextWin32Message(Boolean& fQuit)
at Microsoft.MediaCenter.UI.Dispatcher.MainLoopBody(Feeder feeder)
at Microsoft.MediaCenter.UI.Dispatcher.MainLoop(LoopCondition condition, LoopBody body)
at Microsoft.MediaCenter.UI.Dispatcher.MainLoop(LoopCondition loopCondition)
at Microsoft.MediaCenter.UI.Application.Run()
at ServiceBus.UIFramework.PageBasedUCPService.Run()
at ServiceBus.UIFramework.UserControlPoint.Launch(String args)
at Microsoft.MediaCenter.Internal.LaunchMediaCenter.LaunchMediaCenterHelper()

Can anyone help me? Thanks in advance.

In the absence of suggestions, I have done a System Restore which has resolved the issue.