Right click on the AH2 icon, select properties, and click on the last TAB. In here, you have a option for running AH2 in 256 mode. THIS NEEDS TO BE UNCHECKED. I have no idea why, but it was checked on mine. I just downloaded AH2 patch 40(full version) last night, so dont understand why it was checked.
So, uncheck it and see if this helps. Good Luck
Spivey