This problem has been around for a while. I consistently have it on my Vista laptop when I have an external synth connected. Using Coyote Forte, I rarely see it. If the problem appeared after working fine, something must have changed such as an update or the addition of some hardware. You can try a BIAB reset to factory settings and see if that helps. Otherwise, search the forum for 'Access violation' and you'll see plenty of posts with suggestions that may help you. Also, make sure you have the latest updates for your computer and BIAB.

R