ati radeon hd2600xt 256 ddr3

[overclock17]

Hi guys i got a problem
i just bought a new pc with

asus m2v and somthing i dont rmember but thats not important
1g ddr2
ati radeon hd2600xt 256 ddr3
3500+ 64bit amd athlon

ok heres the problem i know its about incompatibility or something like this.
i can play counter-strike source fine and alt-tab it then come back and play
but i cant do this with 1.6 WTF! ?
i launche cs 1.6 i play its okay then when i alt tab out
and come back in i got this stupid window



i got the sound , im in the game i could maybe kill someone by guiding myself with the sound
but i dont have the image

if someone could help me that would be very apreciated