I wonder if the ground and neutral lines have been switched either at the generator
output or the Xantrex MS2000 input. Can you check that? (They sell something at Radio
Shack to check polarity and ground. Or someone a the marina may have one already.)
I found my boat's shore power plug
was wired in exactly that way. (Discovered while installing MS2000.) So I opened up the plug
and fixed it.
(By the way, I'm having a problem with my MS2000 -- it won't chanrge the batteries when connected to shore power. Did some Google
searching/researching and came upon your thread that way.)
Good luck with it.