Apple IIe MMU faulty?

["Greg Andrzejewski" <pressyourluck85@yahoo.com>]

Hi,
    I have an Apple IIe enhanced that appeared to be having memory problems. 
The problems only occur when I have the 80 column/64k card installed. The 
same 80 col/68k card produces no problems when installed in another IIe.

When I run the self-test on the faulty IIe with the 80col card installed, it 
stops and displays "MMU" on the screen.

I have a copy of MECC Computer Inspector which consistantly finds some error 
XX in the aux memory 010XXX.

Is this characteristic of a faulty MMU? What else should I check? Also, can 
I swap out the MMU from a platinum IIe to see if the problem goes away?

Thanks,
Greg