Texture Problem on Warcraft 3

Hello there guys.

I have a big problem in warcraft 3 and i don't know how to fix it. I had a Geforce FX5600 128MB and all the things was good.

I have an old computer system with AGP8X motherboard. I changed my graphic card to Geforce 7600GS 512MB DDR2 AGP several years ago and warcraft problems starts!

In Areas with snow on it (even some) i have texture problems. take a look at this picture :

http://i56.tinypic.com/2n7oc3a.jpg

I installed several Drivers (newer and older) and lastest patch for warcraft 3 (1.24 right now) but still i have the problem. i didn't overclock my Graphic card and i have a good power supply. i don't have any problem with other games!! only warcraft 3 :(

what can i do?

thanx guys :)