I came across this issue myself this weekend,
"When trying to scan from printer direct or via all-in-one centre the printer starts the scan and then shuts down/re-starts? Any ideas/seen this before? Thanks Steve"
Spent ages searching the web for a solution for this one, but in the end the old "2 - inch drop" was all it really needed...
Just took the two screws out of the left of the flat bed scanner glass section. Then removed the left hand grey panel that snaps in place to the left of these screws on the side of the printer. Then managed to get enough leeway out of the flat bed scanner glass holder, to reach in and give the scanner bar inside a bit of a shake.
Switched off and on again, and the scanner bar reset itself to the correct location, which is, when working correctly, out of site underneath the A4 indicator bar.