Does it do this if you run the BIAB window full screen (maximized)? My nVidia system with an lcd monitor has problems with BIAB if it is not maximized. Sounds similar to your problem.
What is your memory config in your computer? You might try going into the bios (if you are comfy with that) and change the settings for your system memory speed and type, especially if you have added memory lately. Are you using a built in video or an add on video card? If you have a video card, did you disable the onboard video and/or release the memory used by the onboard system?