Unable to open TWAIN source

This post is a deviation from my general blog theme, but I simply had to post it.

Issue: my Canon LiDE 25 scanner was working for several years on Windows 7 x64 English Pro but suddenly started to show error “Unable to open TWAIN source Please check connection Then re-start Toolbox”

Solution: add C:\Windows\twain_32\CNQL25 to PATH environment variable.  Problem solved!