Fixedheader columns not lining up in Firefox

I cannot for the life of me figure out why this is not working in Firefox but is working in Chrome/IE

http://tinypic.com/r/903mhi/5

Usually when I scroll down to the abs bottom or abs right of a fixed header table the last row/column becomes out of alignment to accommodate for the scrollbars and realigns as i scroll back up/left.

But firefox doesn't seem to be doing this at all. It just seems to push everything out of sync.

Any ideas?