Settings are different on different machines and you did not state what yours is, generically speaking:
1. Original type (try different ones)
2. Edge erase (To delete the area)
3. Make a copy (see if it is a hardware issue)
4. Try setting the original size (Possibly it is scanning past the edge of the page)
Each time we attempt to scan coloured pages (anything darker than canary - ie. pink, blue, green) as grayscale with the background suppression on we get a darker grey block along the feed edge. See Below.
This occurs with feeding SEF, LEF and on the glass. Is there any way to use background suppression without getting this block? Any ideas what could be causing it?