Gpu is not responding error

i updated the game this morning and at first it started out fine and just barely some lag as it always does. i load into a map and started playing around for a minuet and went to open my browser to check some stuff on the site and when i pulled the game back up i got a error i have never gotten while playing
i keep on opening the game back and it would do the samething but this time when i loaded in the map it did it. i tried to exit off when my screen goes black then it brings back open my browser and give the error and then a crash report.
i decided to try one more but it did it when i launched the game.
im hopeing some one might have a answer why its doing this and if anyone else has the same problem