using the jQuery progress bar and some $.ajax({}); requests to poll our server when processing / calculating items.

Normally this works fine, however, I have noticed recently that the progress (polling) always "stops" when running long processes (say 13000 items or so (in this current example it stops updating the progress bar at around 40-50%, roughly (but not always) 10 mins in)), but server still processes each item (the tomcat logs prove that the request is still running).

Anyone had this kind of an issue before?  I'm not really sure where / how to start debugging this issue.

Does IE (we only support IE) have some kind of problem with long running requests or too many requests in a time-frame?

NOTE: I have tested this with a polling interval of 100 and 1000 and it seems to stop updating roughly in the same area. (its worth mentioning that this isn't due to any error caught or thrown in the request itself (at least not that I know of) as the time it takes and the % its on when it stops is never the same).

I'd appreciate any input at all, even just to push me in the right direction.

P.S. this is most likely an ajax problem, but I didn't know where else to put this topic ;) 

Regards,

Stig.