I have been playing Diablo 3 since the day after launch on my desk top. It runs the game like a dream (not a single moment of FPS drop in the 20+ hours I have played). However, every 3rd or 4th time I boot the game, I get greeted by a wonderful grey box and a dialog that mentions that a D3D device has failed to be created. So, I go into the Diablo 3 folder and delete the prefs file and all works well...temporarily.

I would like a permanent fix please.

If you require any more information, let me know.