MSIE clearing something it shouldn't

[protohominid]

I'm at my wit's end... Of course, with MSIE, when aren't we at our wit's end? :)
I've recently built a site that has a 3-column layout; fixed left & right widths with a fluid content center (no, the content isn't ordered like it should, but I have yet to find a system that works for this site). The pages of the main site (volunteercentral.net) work fine in IE, but when the page is rendered by a secondary site that inserts its own tables into the content area, IE is clearing the tables of the right column. Here's an example page:
http://www.volunteersolutions.org/bvu-maryland/volunteer/

The problem is that I can't control the dynamic content that the secondary site is inserting (the damn tables). I've tried everything I can think of as far as applying styles to the <table> tag, but IE is really stubborn (what else is new).
I'm hoping somebody out there can give me some help without wasting too much time on this...
Thanks in advance.
sb

[ray326]

At first glance it looks like box model problems with IE making some things too wide, causing them to push down under their neighbors. Of course that's the opposite of what it would normally do but it is being presented with a load of little layout tables.