display problem in vista 64bit!

[Phatzy]

ok i dont know if its been posted before (i've looked)

right, my screen goes blank like a tv is not tuned in, everything is still working you can hear sounds but no display.
i've installed newest drivers and problems is still here, is it common?

specs is below

 

[Phatzy]

it only happens when a game is loaded or a screen saver pops up, then i have to restart the pc. browsing the web, watching films etc, its fine.
i may think its my graphics card not good enough for vista.

anyone know anything about this? as i just installed this