The problem could be that I'm running the demo version. Perhaps they revised the D3D drivers in the final release.
By the way, does anyone know of any place online where the PC versions of Blitz or Blitz 2000 are sold? I've checked all of the major online stores, eBay, and my local CompUSA's bargain bin, but can't find it anywhere. Is there some obscure e-tailer that sells either of these two games?