browser bug?

Hi, I'm running PHP 4.2.1 as a module of Apache 2.0.39 on XP. Everything works fine, except in the case of certain output from my scripts, which a certain browser--which shall remain anonymous (but it's initials are IE6)--can't seem to handle, and responds by having the browser equivalent of an epileptic seizure. The PHP script isn't doing anything special. It just checks if some session vars are set, and the rest is just plain HTML, with tables. Netscape 6.2 handles it perfectly. I even installed Microsoft's latest IE patches, with no luck. I'm wondering if anyone else has encountered the same bug, or whether I should take this personally. Thanks!