"It seems problems with tables might have something todo with it..."

It's an error, but an error I expect most browsers will tollerate. The fact that when you save the web page the tag disappears says to me that the browser recognises that it's not meant to be there and ignores it. Even if it is meant to match up with a <td> somewhere it won't matter if it's ignored since &lt/td> is optional and not required in table definitions.

I believe the bug with Firebird is that it's not adopting with width specified for this column in the CSS.