http server access problems

Hi,

Our client has reported an apparent instability of our web service while
testing from his site. Sometimes, no response is received from our server.
The problem seems to occur randomly. When this happens, no entry concerning
the http request is found in the access log on the i. I first thought the
problem must be in the client's own application. However, in our firewall
log, there are some entries which indicate that a request was sent to the i
but there was no response from the server on the i.
In order to try and reproduce the problem, I have set up a remote access of
our own (up until now, all my tests were carried out from an internal IP
address). I had a couple of timeouts with no response quite rapidly, so I
stopped the server on the i, and purged the logs to try and make things
more readable. Now, after restarting the server on the i, I am unable to
reproduce the problem, despite sending nearly 100 requests.
Any suggestions?

TIA