Task switch issue

Yesterday, I task-switched (alt-tab) out of FS9, as I frequently do. When I tried to task-switch back in (which has never caused any issues), the picture wouldn't come on, and I could only hear the sound (and then I didn't sound totally right, but that's another story that's probably linked to the main problem). Pressing alt, the menus did show correctly, and if I did alt-enter from the (invisible) full window, it did switch to windowed mode. So, I did another alt-enter from windowed mode, but then the FPS was really, really low (like, 6 or less, and I've got mine limited at 24, and shift-z constantly shows a 23.8 or 23.9 rate, and my machine does run it higher, but I prefer having it limited); in addition, this was in the Level-D 767, and the FMC text was gone, too (and after toggling it off, it wouldn't come back on). All this is a first occurrence in six months of having my present computer. Any thoughts as to the cause (apart from drivers, which I'll now update)? Running FS9 on a 21.5 inch iMac (in Windows 7/Bootcamp), which otherwise runs pretty well. Thanks, Nicolas in CYOW