[0.295 Bug][Graphics] Fog of War gone after alt+tabbing

The game was running fine in fullscreen mode. Then I alt+tabbed and opened it up again. The fog of war was almost all gone and although the picture unfortunatly does not show it, I could see the outskirts of a blue city through the FoW a little lower. Here is the picture:

http://www.screencast.com/t/ZjFmMjhlZ

I alt+tabbed again to save the screenshot and when I came back, the fog of war was back down there, but there were some weird designs on the cloth map on the upper left corner of the map. Here are the pictures of the good fog of war and weird graphics, respectively :

http://www.screencast.com/t/OGM4OWZkOW

http://www.screencast.com/t/M2UxNzBi

(Note that I just noticed that the top part of both pictures isn't part of the actual true screenshot, it probably appeared when I used paint...)

Here is the debug :

http://tanisgosu.pastebin.com/YGHdZDz5

By the way, like 99% of the debug.err consisted of this line : DebugMessage:  ValidateDevice::Reset. The file was 2.5Mb big .