Since it appears you have only patched UT3 to 1.3, install UT3 patch 2.1 if you haven't already because it is required to use the UT3 Titan Pack. Also, the most stable drivers from Nvidia seem to be the WHQL 182.50 (the latest WHQL driver released before 185.85). Nvidia recently released a new WHQL 186.16 driver, but appears to have some of the same issues that the WHQL 185.85 driver had.
Try Nvidia WHQL 182.50
Avoid Nvidia WHQL 185.85
Nvidia WHQL 186.16 - up to you to try or not
Before installing new drivers, I would go to the device manager and uninstall your video card drivers. Then run driver sweeper while the PC is in safe mode and delete all the files in the "Nvidia Display" category.
Some other things I would do is look for any yellow question or exclamation marks in the device manager. Then I would go to System Properties again by clicking "My Computer", then right click, go to properties, and then click the "Automatic Updates" tab. Go to the link towards that bottom that says, "Windows Update Website". Install the validation tools that are required, then click "Custom" and install all the high priority updates. If you don't want to install service pack 3, then uncheck the box. Going to Gigabyte's website and updating the motherboard chipset drivers is always recommended as well.
UT3 Patch 2.1
http://download.beyondunreal.com/fileworks.php/official/ut3/UT3Patch5.exe
Driver Sweeper:
http://downloads.guru3d.com/Guru3D---Driver-Sweeper-(Setup)_d1655.html
Nvidia WHQL 182.50 32bit WindowsXP
http://downloads.guru3d.com/Forceware-182.50-XP-32-bit-WHQL-download-2235.html
Nvidia WHQL 182.50 64bit WindowsXP
http://downloads.guru3d.com/Forceware-182.50-XP-64-bit-WHQL-download-2234.html
"A problem has been detected and windows has been shut down to prevent damage to your computer......(yada yada yada)...
...
Technical information:
*** STOP: 0x0000008E (0xC0000005, 0x00000000, 0xBA297B44, 0x00000000)
This could be the result of a windows, hardware, or hardware driver/s issue. Normally updating windows, changing drivers - hard to determine without knowing exact hardware, or doing another HDD reformat cures the issue.