I shouldn't have said a goddamn thing. My scanner has decided to randomly cease working (or Photoshop has decided to randomly cease thinking it's got a valid TWAIN entry). Thought, the only thing I changed since it was working last night or so was to install latest Zone Alarm; they must be conflicting in some weird way. Try to re-install older version. Won't let me; says I have to uninstall it and lose all settings. Ok, let's try uninstalling and reinstalling scanner. No dice. Uninstall Zone Alarm completely. Still doesn't work. Give up on troubleshooting more tonight. Reinstall latest Zone Alarm. Worry.