Is this symptom of video card issue??

Hey guys! I've got a weird freezing issue here with windows SP2, I was wondering if its a symptom of video card problem?

more specifically, just recently after migrate from LAN to wireless connection, my system start having such freeze problem randomly, when it happens, first thing is that the desktop screen freezes, i am able to move the mouse, but the system speaker generate beeping sound along with the mouse movement. and then (about few secs) the screen flashs into black (but not blue screen), then after another few secs, the screen goes back to original desktop and freezes there forever (sometime it goes back to normal, like nothing was ever happened).

I've reinstalled the wireless driver, no luck.
I've reinstalled the VGA driver and the problem still exist. Friends were suspecting its the video card, so what about your guys here?

please help..thank you

PS:
the wireless card is onboard with the motherboard ASUS A8v-e deluxe.
the system is 3 years old and windows is about 1 year?
the video card is Gecube X800XL bought with the system 3 years ago.
all fans are running fine

it would be a great news to me if you were right. i love my X800XL, really not willing to replace it.

what sort of windows problem could it be? by the way, there are no any dumps or event logs been recorded in the Event Viewer.