Today, I thought of the only other thing I had changed since the last time the scanner was known to work, which had slipped my mind last night. The night before, I was playing around with the Services control panel (this is Win2K) and disabling or changing to "manual" things that I didn't think I needed. One of these was "Still Image Service", which I have never known exactly what it does. It was "Still Image Monitor" under Win98, I think; I had killed its task/process sometimes and never noticed a difference, so I remained clueless. Well, apparently it has something to do with TWAIN, because when I was going down the list of services starting them to see if I could ferret out the right one, the scanner went "zzt! zzt!" (the scan "head" moving) when I started that one. And lo and behold, programs were then able to actually open TWAIN and acquire again. So I switched it back to "automatic" starting. I still don't know exactly what that service does, but at least it wasn't something more serious going wrong.