Something similar happened in the DX 8 beta versions of AH right before 1.08 came out. That was caused by nVidia's drivers. If it's happening on both your systems I'd suspect either a video driver conflict with AH, or the AH patch you got may have been corrupted. Since I'm guessing this didn't happen before the patch, you may just want to bite the bullet and uninstall AH and download and install the full version. The uninstaller won't remove the settings directory, so for a complete uninstall, I'd remove this as well. (Copy any custom sound folders or special gunsights before you do this though.)
Before reinstalling AH, first try going into it's settings folder and removing the video7.cfg file. Reboot the computer and start AH. It will reprompt you for video settings. On the GF 2, try the 12.41 drivers, I know those work well. On the GF 3, the 21.83s are the newest I've tested that work ok. (The 23.11s were buggy when I tested them, I haven't tried the new 27 or 28 series drivers yet.) Make sure you are removing the old drivers before installing new ones.