using 2 versions of FP problem

I encountered a problem that I believe must be because two of us have worked
on a website and we have different versions of FP.
When I built the site and uploaded it, it was perfect but then my partner
downloaded it to his computer, made a couple changes and uploaded it to the
site again. My view was then altered as some of the pages were very narrow
in view even tho we had them set at 80% width.
Am I correct in saying it must be the different versions? I'm using FP2003
and he is using FP2000.