4
Two more modules have been added to my list of unistallables: xLink and AMS. At the same time, I've installed other modules with absolutely no problem.
I'd missed the FAQ since I was looking for it in the modules section. I'd recommend putting a link to it there as well. It was the most helpful info I'd found so far on the subject, but no luck so far. I thought it might be conflicting moduels, so I uninstalled any likely suspect, but again to no avail.
I did also double-check group permissions, and all seems to be in order.