Screen corruption and BSODs with nVidia Geforce GTX560-Ti

[partof]

I've bought a new nVidia Geforce GTX560-Ti recently to upgrade previous nVidia Geforce 8600GTS.
After a few hours of use i've got corrupted screen and then BSOD. Basic check of crashdump file shows problem with nvidia videodriver.
I can't reproduce this behaviour as it happens from time to time in a few hours while i doing basic tasks such as browsing internet, writing documents.
Such problems never happened before with previous videocard and same computer setup.
After I've stoped and disabled UltraVNC service and then rebooted my PC, BSODs never happened again.
Running my PC for a three days now. No screen corruptions, no BSODs, no problems in games, no graphical glitches or artefacts, etc.

Things i've tried before i've stopped and disabled uvnc service:
Replaced old 450W PSU with new 600W PSU.
Downgraded videodriver.(Tried 296.10 and 295.73 WHQL-versions, clean installed)

My config:
MB: Intel DP35DP
CPU: Core2Duo E6750 2.66GHz
MEM: 2Gb DDR2
Video: nVidia Geforce GTX560-Ti 1Gb (Using 296.10 WHQL driver)
PSU: 600W
OS: Windows XP x32 SP3
UltraVNC version 1.0.9.6.1 without mirror-driver.
No overclocking at all.

[Rudi De Vos]

Strange, i would think that only the mirror driver has an impact on it.

You say it crash after a few hours being connected with vnc.... or while vnc is installed and you work local.
When you are not connected, the vnc service doesn't do a lot..at least nothing that can have a big impact on the graphical engine.

Strange issue, but don't have an idea why it crash ... sorry.

[partof]

It crashes when i work local, without uVNC or RDP sessions from network.
Basicaly, uvnc service was running background, updated from time to time and used for years without problems. But after described changes to my PC configuration those screen corruptions appeared.

I can upload kernel memory crashdump and uvnc config file somewhere, if it helps.