[imp] 404 error when sending..

[Errol Neal]

Hi all,

I am trying to troubleshoot an issue that my users are experiencing when
composing a message with IE (Internet Explorer). If they take longer
than 30 seconds to compose a message, when they hit the send button,
they get a 404 error. Hitting the back button and hitting the send
button again sends the message right away. 
When I look at the logs, there is not even a POST entry in server logs.
I am using horde 2.2.5 and imp 3.2.4
I am not sure where the problem could lie. Maybe some sort of keep alive
issue? I am using HTTPS urls. I have not tried to troubleshoot this
problem w/o SSL. Any of you folks got some ideas to help me solve this
issue? 

Thanks!

Errol Neal