Vostro 1000 Blue Screen with 'garbled' white vertical lines?

Hi

Hope somebody can help please. Not having much luck elsewhere. My 8 month old Vostro 1000 irregularly locks up with the blue screen and (what I can only describe as)  'garbled' white vertical lines (guess these garbled white 'lines' are supposed to be the error text). It seems to be happening more often now, but at no particular time, or event, or software use, etc.... completely random.

Running Windows Vista 32 bit Home Premium with SP1, which was previosuly configured for auto restart, but disabled that to see if the garbeling stablises so as to get the bluescreen 'STOP' info - but that did not help, and now manually con-alt-del reboot.

On rebooting (normally) to Windows the recovery message is

Problem Event Name : BlueScreen

OS Version                 : 6.0.6001.2.1.0.768.3

Locale ID                    : 2057

I click the 'check for solution' button, and after a while it closes the box with absolutely no further info.

Have checked for the latest device drivers, and suspecting that it was a graphics problem reinstalled the ATI drivers (Radeon Xpress1150) - but the problem is still occuring. Have done the same with my anti-virus software (Trend Micro) - which is the latest and up to date with viral data files, and do a full scan every few days.

I'm at a loss now, and Dell do not seem to have online chat or email services for the vostro brand.....

Thanks, and appreciate any help or suggestions

Garry