display driver stopped responding and has recovered

Please help me this is incredibly frustrating especially because I've never had this stupid problem before. Every time I play a game and do anything as simple as click something, I.E. playing Skyrim and i press tab for menu, my screen completely goes black and then comes back in seconds with a display error message with this annoying unreadable driver error nvlddmkm. I mean really what the hell does that mean. I used to have this problem before when I downloaded some new Nvidia drivers online but then the problem ceased after getting the newest beta drivers 340.43, and after that pc was fine for a good 2 weeks, then the problem came back and I read that the error was related to cooling problems with my GPU so I downloaded MSI Afterburner and manually cranked up my gpu fan speed to 100% (kept the preference to manual not automatic) and that completely stopped the problem for about another week. The problem came back recently about a day ago but it wasn't going berserk until about now and I think its the fan speed because even though I cranked it up to 100%, on my GPU meter it shows that it goes back down, even though I myself manually set the speed it goes all the way down to 20%. Sometimes in the middle of a game the lag gets crazy until my display shuts down and shows that error message, then i check my GPU meter and it shows the fan speed going at 20% and the heat rising 75-80C. now my idle temps range from about 30-45C and load temps are 50-60C sometimes 65-70C I guess thats pretty normal for a card especially a factory OC card.(Nvidia GTS 450 OC) I have no idea whats wrong with the card and I really don't wanna buy another one at the moment, I still hope its just cooling problems but I really don't know, because the card keeps going back down by itself even though i have manually set fan to 100% via MSI Afterburner it shows the fan speed dropping on my GPU meter, also this only really happens after about 4+ hours of gaming but before when GPU ran the fan speed at 100% normally it wouldnt even hit 65C after about 5+ hours of gaming but usually after I restart the system everything seems to go back to normal until that point where the GPU starts getting unstable again. I'm thinking of buying a couple of fans for my case to keep everything in there more cool but first I wanna find out whats wrong with GPU.


Thanks in advance!!