It could be a video driver issue. I've noticed this happens on some later nvidia drivers as well.
You might want to try it with WineD3D and put -screenmode in the shortcut command line to select the resolution. Depending on which version of Incoming you have, it will either go up to 1024x768 (original version) or 1280x1024 (version bundled with Incoming Forces).
If you have problems with the newer versions of WineD3D, try version 1.6.2. That's what I'm using in XP with a GeForce 6800 GT (94.24) to correct the HUD rendering.
The frontend runs really fast (v-sync seems to be ignored), but it appears to be locked at 30 FPS in the missions, so not a big deal.