Textures are missing in Heroes of Might and Magic V on Windows Vista 32-bit Business.

Textures disappear right from the start of the game. After some time, everything returns to normal, but as soon as you exit to Windows and then go back into the game, the same problem occurs again. Textures can also start glitching during battles and when entering a Castle! All the latest drivers are installed, and I've tried reinstalling Windows and the game, but nothing helps. Please help, anyone. Intel Core 2 Duo E6850 3.0 Ghz 4 Gb Ram Nvidia GeForce 8800 Ultra 768 Mb Here's an example image: