Thanks for all the feedback.
I think I figured it out. After reading EaX's suggestion for video setup, I played around with some of the settings. It seems that if I run SEV in a resolution higher than my native desktop mode (I keep my desktop @ 1152x8-whatever, and was running my usual 1280x1024 for games) this problem will happen. I had some idea this might be the problem because the problem was presenting itself when I was clicking anywhere on the lower 10% or so of the screen, which seems to correspond to my toolbar given the difference in resolution.
If I run the game in 11x8, there's no problem, and there doesn't seem to be any problem in 1024x768 either.
I guess for completeness in reporting this as a potential bug, I am running XP Service Pack 2, with the 6.14.11.6218 Nvidia drivers set on a GeForce GTS 8800, and the August '07 revision of DirectX.
If there's any more information that would be needed, or there's a place I should post this information on this bug, I'd appreciate knowing about it so I can give a proper report.
Thanks again for everyone's help.
