Grr! Another reason that more people need to stop using Internet Explorer: it can’t even interpret “width: 100%” right all the time.
I encountered this particular bug in one of my own web design projects today; in one of my pages, a table with the aforementioned width was contained within a fluidly-sized DIV that didn’t span the full window. Any sane browser would size the table to fill the DIV, but not Internet Explorer… no, it sizes the table to take up the full width of the window. Gah! And even worse, the fix suggested at the link above doesn’t work for all page layouts; I couldn’t get it to work with the particular way I had the sidebar set up on the site in question (which is still in the testing phase and hasn’t been rolled out, for the curious).
At least in the layout I was having difficulty with, the problem wasn’t unique to tables, either; even a paragraph with a style of “width: 100%” would flow over into the sidebar!
And people wonder why IE is such a headache for web designers these days…