Noutje:
Did you made your product descriptions with HTML-area or with another editor?
The used HTML in your descriptions is maybe causing the problems in firefox because what i believe is that firefox uses tables in a different way. I see in the source file that the description uses fixed table widths and also there are some issues with some tags that are being closed but not opened. According to dreamweaver validation there are some misused span tags and some li tags.
You description pages really look messed-up in Firefox but not in IE.
I guess you are right. I was using frontpage to built up the html codes and pasting them into zencart. So, what should I do in order to prevent this firefox problem? Another editor? If so, which one? Thanks a lot!