thanks for answering
yeah i know what 3dnow is,but i still think it's the cause of my problems. here's my explaination:
once my cpu fan stopped, and the system hang up. the radiator was really hot. and next time i run a program that used the 3dnow enhanced insdtruction set, strange things began to happen. at first i reinstalled directx and the graphic card drivers. it didn't make any change so,remembering what happened to the fan, i got a little bit suspicious.i run some kind of cpu benchmark( don't remember which one ) which was displaying an animated scene. there were two versions of this test: one that did use 3dnow and one that did not. guess, which one was working correctly... note that the benchmark was using cpu only, without the acceleration of direct3d or something.
so i swapped processors. i got my friend's duron 1000 and made an exchange. while my system was functioning correctly, his machine made strange things like mine before.
that's why i do think the problem is in the cpu.
i don't know the processor's internal structure but i suppose that the block responsible for interpreting enhanced multimedia instructions was damaged (however silly it sounds)...
i don' play games very often so i feel no need to buy a new cpu, however.... ;D
but, now i see my mistake. i should have formed my question in an another way:
is there a way to make windows not to use the enhanced 3dnow instruction set?
thanks in advance for the answers