BIG problem generating thumbnails
 

I'm using Windows 7.
I had no problems at all generating thumbnails until tonight. I took a look at "Frame and thumbnail capture" preferences -- that's all, I just took a look, to the best of my knowledge I didn't change any of them.
After that, I click "Generate Thumbnails", set the receiving directory, and press Save. The video keeps playing, but the window freezes and stays on top, I can't minimize it, resize it, or move it around. I also can't stop the video.
About all I can do to regain control of my computer screen is start task manager and kill BSPlayer.
Anybody know how to fix this?