Strange tcpsvd behaviour

I'm running a fnord/tcpsvd web server, and sometimes ("sometimes"! Don't 
you just hate that!) people with Internet Explorer can't connect. 
Switching to tcpserver (ucspi-tcp) helps, but I would really like to run 
a clean Debian system.

I logged my attempts with tethereal (libpcap format). The first two logs 
show IE first failing, then succeeding. This is from the same client 
machine, just a few minutes later.

When IE fails, it fails consistently on every attempt. The third log 
shows FireFox succeeding at a time when IE would fail. This also from 
the same client machine.

http://www.lysator.liu.se/~clacke/http-dump-ie60
http://www.lysator.liu.se/~clacke/http-dump-ie60-working
http://www.lysator.liu.se/~clacke/http-dump-ff91

I can't see any obvious difference between these attempts that would 
make tcpsvd spontaneously FIN:ing the first connection, but not the 
other two. Any ideas?

    /Clacke