icecast on-demand streaming iPhone

We are using icecast for live and on-demand streaming of recorded live
sessions.
The problem occurs with the on-demand streaming on IPhone's: the recording
starts playing and after 5 - 7 minutes it starts over again from the
beginning.
We think it might be caused in the handling of partial content. The icecast
log shows at the first connection a "206 Partial Content" answer, but a
second or third connection shows a "200 OK" answer. The serving of the
mp3-recording with the apache-webserver handles it OK. Also when using with
a PHP-script, which recognizes the "range", the handling is fine.
I already tried to solve the problem in the source "fserve.c", by
introducing the ETag and Connection: Keep-Alive, but this does not solve the
problem. 
Has anybody seen this problem before and found a solution for this ? Many
thanks in Advance
Henk