If I'm reading things correctly:
He didn't mention what version of Win he is running, but did say SL 10.
It
never worked under SL 10, but it once did work under SL 8, but SL 8 won't open now.
Corruption in
Windows system is perhaps likely, especially if there was an update recently.
It could have been a corruption of the twain.dll file that is used as an intermediary for WIA or the variable path could have been changed.
To my knowledge TWAIN support shipping with
Windows stopped with ME (so it's been awhile and that makes sense, I haven't messed with TWAIN in a very very long time) and it's up to get it supported under WIA or have drivers shipped with the programs.
Corruption in the system could very well be where it is at.