GTA IV video driver crash + low performance in vista

[T_L_O_T_D]

hey guys

i don't know exactly what's the problem! but few days ago i installed GTA IV then in my fisti benchmark in highest render setting and medium texture and my view distance was 55 and other setting on 100.

my average FPS were 26-28 in vista ultimate sp1 32 bit! my graphic card is 4870 512 mb.(ASUS)

then in divice manager i unistalled my vga then installed again with new driver(8.12). in first run game was smoothly! my fps increased to 38! but

after restarting my computer,i lunched the game again to check bechnmark again but again fps reduce to 26-28!

i overclocked my vga to

engine:800

memory:3700

but nothing happened!

i installed the game on XP sp3 and also installed latest driver(8.12) too!

checked the benchmark.game was completly smooth and fps was 38! i restared the pc and checked again it was OK! 38-40 fps.

but i don't understand why it happens on my vista!

for example in game sometimes i receive driver crash error message or in game while i playin bowling it goes to blue screen(sreen of death)

dump memory and after that restart!

i have all of this problem in vista! any idea?

[Mehhh]

Are these 2 diff operating systems installed on separate pc's or the same ?

If different then assuming you moved the graphics card from one pc to the other, it may not be easy to say, pending the differences in hardware & software installed on the pc's .. Its normally good to list system specs, OS, cpu, memory, card..

Otherwise you may try checking what processes are running in the background.. Perhaps it is a driver issue.. Another gamer on here has been havin probs w/ framerates but he says his are WAYYYYYYY low.. The ones you have frankly, sound good compared to most .. Alotta ppl I seen have frame rates in the 20's .. again R* stresst ppl can't expect the best outta the game even w/ good pc's ..