HTML tables broken

I’m desperately trying to get tables to work as I run a movie review site which I am trying to port to WP and at the bottom of every post we have a table with various information (rating, actors, director etc.).
When I create a table in the WYSIWYG or in the code tab, changing between tabs seems to delete all but the first row in the table! Please please fix this as I cannot move over to WP without this functionality, and editing the whole post without using the WYSIWYG is just not feasible.