Fileupload timeout

Where are the possible places that a fileupload could time out?
I am aware of:
<system.web>
<httpRuntime maxRequestLength="2097151" executionTimeout="280"/> </system.web> <httpRuntime maxRequestLength="2097151" executionTimeout="280"/>
</system.web>


But My fileupload still times out at 2MB and at different times rather tha just the 280 seconds. So I think there must be a timeout and max request length somewhere el ...