About my computer and printer problems...
First, thanks to those of you who have offered suggestions. r.e. wolf, I've tried the complete unplugging and disconnecting and rebooting numerous times (including disabling all the USB functions that the printer established before re-connecting and re-booting). No luck.
I just Googled "Press F1 to continue" and learned that error message can be caused by anything from a new hardware installation to a failing hard drive, or even a dying CMOS battery. I'm kind of betting now on the failing CMOS battery (although that also is what keeps the date and time function working—and they still are so I don't know—but this computer is now 5 years old and could need a new little battery.)
Maybe the two problems are related and the computer is sensing the printer problem as an improperly connected piece of new hardware. Maybe the USB hub I added has a problem and that caused all the rest.
But MAYBE it's the "C," trying to convince me I need a new computer.
You know, one of those dual processor, faster, sleeker, sexier ones! *Drool* I mean, the computer I'm using is one I assembled from individual components 5 years ago. Even though I had help from our I.T. guy at work, there was a lot of "trial and error" (heavy on the "error!").
Oooooo. It IS tempting.
But first I'll talk to my I.T. guys again and try everything I know to try. And to keep this "problem" in proper perspective, I CAN still use the computer and printer. The printer still prints just fine — it's the scan function that is questionable. And I can still scan using commands from Photoshop.
I tend to be "conservative" (read: "tight") with my money, so unless it fails I'll probably keep using this machine for a while yet.
Meanwhile I'll replace the CMOS battery and see what happens. That's probably the cheapest possible fix.
Stand by for further news as it breaks (pun intended).