It's a common SA:MP Bug.. Started to happen to me around the release of 0.2.3 and came along in O.2X...
I Don't think you can't really help it, Even re-install might not help..
The only way out (literally) is by pressing the 'windows' button and go back ingame.. Your graphics should be fixed by then, for a amount of time and limited movement, until it comes back...