A regular IISReset /Restart turned into forcing a reboot. The stop worked but the start was unable to succeed.
The message was:
"Cannot start a new login session with an id that is already in use"
IISReset /Start reported the same problem.
NET STOP W3SVC reported the same problem.
In hope of finding the proper svchost.exe to terminate, I ran "tasklist /svc" but was unablet to see W3SVC among the tasks handled by one of the svchost.exe instance.
So, the last resort was to force a reboot.
Anyone has seen that one before or would know how we could have resolved that in a smooth way?