Wing Commander Prophecy Video Problems


I recently tried to play WCP again after a while of not playing. However, I had problems with the video. All things that should be transparent are not. For example, the AUTO light is in the middle of a big blue square, as well as a lot of other gauges. This ONLY happens in Direct3D mode. Since I played last I have upgraded to Win 98 (from 95) plus I updated to DirectX 7.0 and updated my video drivers. I had this problem under Win 95 too, so I think it is with DirectX or video drivers. Anyway, my questions are: How do you downgrade DirectX? Is there a WCP patch that lets you play in OpenGL? Also, does anyone have definite answers to what is going on?
I have a:
Pentium II 233
Diamond Viper V330 AGP 4mb (OEM version)

Thanks a lot!
DX 7 is almost certainly the problem; I'm afraid I don't recall how to get rid of it. It isn't done using Add/Remove Programs.
Before I bought my Voodoo3 card I had the same problems in D3D mode. I also had two 4MB cards, a trident and a cirrus logic, but no viper. Perhaps it has something to do with the 4MB's as this was long before DirectX7 was even out. DirectX7 is ful of bugs, though....

Why don't we do it in the road?