WebService not responding

[Franck]

Hi,
got a problem with my WebService. (Win 2003 Web Edition with
Application pools)
It is called from Excel with a linked AutoDual class which provides new
Excel Functions.

All system works good except that some time after a few moment, the
webservice stop responding.

Lookin in logs I found these "errors" :
"Timer_ConnectionIdle" and "Connection_Abandoned_By_AppPool"

Can somebody explain me what are these errors ?
Any ideas ?

PS : Got same system on Win 2000 without Application pool and never got
problem.

Thanks for your help.