This computer is still running Windows XP -- so no OS upgrades are available these days!
All hard drives have at least 50% free space.
I've rebooted the computer and the printer. All other functions on the computer and printer are working perfectly.
I've had the 8700 for maybe six or eight months. There's lots I still can't figure out about it, but the scanning function has been working smoothly (it works almost the same as the C2424 printer I had been using before it died).
I still don't know what 'workflow scanning' means, but from the manual it seems that any scanning on the 8700 is 'workflow scanning' so that's the function I'm using. All I want to do is scan occasional documents on the glass or ADF and have a PDF or JPG appear on my computer for manipulation there.
As to user rights on a network scan -- I'm not sure I understand what that means. This printer occasionally disappears from my network and I have to relocate it, so there could be some network-related problem -- though I have no idea what I might do about it, and in the absence of reason to think I actually have a network problem with the scan funtion, I'm hesitant to mess with stuff I hardly understand!
The only other thing that's happened recently is that the printer has been making a grinding sound when feeding paper. I printed a document last week using cardstock through the #1 tray and the grinding sound immediately disappeared. I don't see how that would affect anything to do with scanning, but that's the only recent change on the 8700, other than the occasional network hiccup. Any further advice or suggestions would be welcome!