"These problems occur when Microsoft Windows is configured to manage virtual memory, which is the default setting. When you attempt to start one of the Office programs, Windows attempts to load the program into RAM. If there is not enough RAM available, Windows attempts to make RAM available by moving code from RAM to the hard disk (virtual memory). In low disk space situations, Windows may not be able to claim enough hard disk space for this operation to be successful. In this case, you may receive the error messages described in this article."
The page is here;
Although you said you have plenty of memory, you didn't mention hard disk space.
Maybe that's the problem?
I get the following message only when trying to open MS Publisher:
"Windows is low on memory, or your hard disk is full. Try closing other programs and freeing up some space on your hard disk before starting Publisher."
This message comes even though nothing else is open. All other programs, even large ones, open fine. In fact, with 1 Gig of ram, multiple programs can be open without problem.