Garrys Mod Clear Screaning

I tried searching several forums for such a problem but couldn’t find anything. The problem im having is that my garrys mod will randomly become clear and I can still talk and type and move around in game but im seeing my desktop as if im not playing. ive tried tabbing in and out and using task manager to bring up garrys mod and it does but its still clear. if theres a way to prevent this or fix it when it happens I would love to know.

Please help,
TheKurd