Gigabyte Ati radeon 4850 512 problem

[groobass]

I am having a problem with my card when booting WinXp,
First of all I have my card connected via hdmi, it is strange that most of times the background color when booting is green not black,
Secondly my system somtimes crushes just before entering Windows saying of a critical error, ccontact driver distributor or change video card,
I tried to reinstall several different Ati drivers and Windows but it still happens even sp3 can't help
my system is Athlon X2 5000 on GA-M57SLI-S4, 4 GB ddr2800 ram at 2.1V, 2hdd etc GP is set to deafault clocks
If anybody has a clue what is the problem please let me know
THX

[IRQ Conflict]

Have you tried hooking it up via the DVI? I know my Samsung monitors HDMI input only works for, well, anything but a computer (don't ask).