When i play HL, any mod, i get this little flicker in the screen. It doesnt effect my frame rate or anything, its just the most annoying thing in the world. Everything that can change or is temporary (like people, the boxes that explode in CS, black out for sniper rifles, things that have been rendered seperatly from the landscape) disappear for like a mil second then appear making a flickering like distubance in just things like that, but not the landscape. And im quite mad because my comp is no POS.

800mhz T-bird
128mb pc-133
geforce2 gts 64mb winfast
asus A7V (W/o audio)
(a piece of crap soundcard)
windows98 se

I just dont know what can do that. Here's the kicker! it didnt do this crap before then when i went to update the bios for my GFX card it started this **** so im thinking its that. Any ideas on what it might be, or how to remove the previous bios installation.
Thanks for your time.