Gigabyte HD 7770 Rev 2.0

Ok i've just finish my build last week and have been having intermittent freeze on my screen while gaming in diablo 3 and once froze while web suffering. 1st of all heres my build, i3 3220, GA-H77M-D3H Mobo, Corsair CX 500 80Plus PSU, and a Gigabyte HD 7770 oc Rev 2.0 GPU, 4Gb of G.Skill 1333 ram (2x2GB). I've ran Performance test with no issues even ran Furmark without too many issues , other than it froze 1 time out of 10. What I mean by freeze is the image will freeze and my mouse wont move and i have to hard reset the pc. At the time i was running F4 bios but updated to F9 on the MOBO. Went it hangs Windows event viewer shows nothing and neither does GPU-Z. Temps are never over 45 on the GPU when it freezes ran Memtest86 with 1 Ram at a time in all slots and all passed. Now I've been reading that this GPU card has Direct X 11 and on the AMD version of this cards it has a minimum requirement of 4Gb of Ram. Now I'm running Windows XP Sp3 and it reads no more than 4Gb of ram, usable its more like 3.5ish GB, and XP only supports Direct X 9.0c. So is it possible my OS is the issue here?Oh ya I'm running Catalyst 12.8 and I've tryed down clocking the GPU from 1050mhz to 1000mhz and i still have the issue.