I think I can help you with this. I noticed a similar behavior with MC, but it's nothing new, it goes back years. I also have a Radeon card, so it might be an issue with the Radeon drivers, or with MC; there's no way to know for sure.
But there's an easy work around... You can restart theater view on an automated basis, and restarting MC itself, or the media server, is unnecessary.
This assumes you keep your MC in theater view all the time...
Just go into task scheduler, and create a task to run a batch file at the same time every day, some unobtrusive time like 5am.
Here's the contents of the batch file which should run from your JR Media Center program directory:
mc21 /mode standard
mc21 /sleep 2000
mc21 /mode theater
That's it. You can change "mc21" to whatever the name of your version's executable is.
This uses MC's command line syntax to make it do things. The first line exits from theater view, but leaves MC still running. The second line waits 2 seconds, and the third line restarts theater view. The execution won't interrupt any streaming or audio playback, but of course if someone were looking at the screen trying to use theater view when it ran, they would see it.
I've been using this for quite a long time now, and it works well. Whatever the cause of the instability, it seems to be in the theater-view/directx/video driver software, and not in the MC core application. Since implementing this, my MC server stays up for months, and whenever I go to use it via theater view, it's always right there ready and waiting nicely.
Hope this helps...