Scanner (Canon n1240u) fails with "invalid parameter"

[MR ZenWiz]

I just had the weirdest experience.  I scanned in a document on my
Canon n1240u scanner and it worked fine.

I tried to scan another, and now I always get "invalid parameter" and
the scanner may as well be dead.

I'm running Xubuntu Precise LTS 12.04 with the Raring kernel (3.8)
using xsane 0.998 and I'm not even sure which sane backends.

I'm hoping this rings a bell with someone.  I rebooted and the problem persists.

???

Thanks.
MR