Hi,
I would suggest you try and upgrade your graphics drivers firstly,
I would not assume your card is falling in and out as this would cause an issue and either reset the graphics drivers each time or cause a BSOD
Anyways If that fails to fix the problem it could be your graphics card? how old is it? and what model do you have? as it could be the card itself?
More information will help us help you.
Cheers,