This morning I scanned a small French reader that Marc particularly liked. At noon I had to scan two pages for Angela, because she'd left them at home. When I went to scan I got this: "Failed to start scanner: Invalid argument".

After much flailing, including re-installing hplip and xsane, and doing sudo
ln -s /usr/lib/libhpmud.so.0 libhpmud.so
I finally got brave and simply moved ~/.sane/xsane to ~/.sane/xsane.old, then started xsane and it worked.

After the fact, I figured out that the problem started when I clicked on the preview pane in xsane and set the size of the area I was scanning to 0. The message wasn't very helpful. (I figured it out by diff'ing the xsane.conf that worked with the one in xsane.old.)

In addition, hp-check reports there's no plug-in installed for my printer, even though everything seems to be working. Go figure.

All this under Ubuntu 9.04 using an HP CM1312nfi MFP.