I recently changed my videocard to GeForce GTX 640 SE (768mb and second hand).I have been having it for over a week.However, 5 minutes ago my cursor blocked on the monitor several times and the whole screen freezed as well several times for 3-4 seconds.Also, the cursor appeared not as a pointer, but as un unshaped colorful thing.I rebooted my PC and the problem haven't occured again.Do you think the issue was caused by the videocard or my OS just freezed and I shouldn't be worried?Thank you.