Problem with Windows VISTA

I have a problem with proper starting of AUTOCAD 2005 with Windows VISTA. I Have
set in OPTIONS window, in Displaying 3D graphics, hardware acceleration .
AutoCAD gave me a possibility of choosing only one driver wopengl8.hdi. It
worked fine, but when I turned off AutoCAD and started it once again it gave me
o notice that wopengl8.hdi driver can't be loaded and AutoCAD sweaches
automatically to software acceleration mode. When I'm trying to set hardware
acceleration once again, acad displays empty list of drivers. Hardware
acceleration works fine with windows XP. Can anyone help me to solve this
problem?