Recently during our upgrade to SEP 11.0.4202.75, a couple of PC's stopped communicating with their Endpoint Management server and the utilization of the PC was fully taken over by the smc.exe process. We spent quite some time debugging this problem but eventually found that a seldom used Windows XP component was causing the problem. It seems that on the PC's in question a Windows Network Services subcomponent called "RIP Listener" was selected. This is not a compoent that we need to use and it is not even selected on our other PC's, save a few. I don't know how or when it was selected and up until this latest version of SEP 11, it has not been the hinderance it now is. During debugging we noticed that there was an exceptional amount of active network routes associated with the NIC card. ( the "ROUTE PRINT" command displays this )
To turn off this subcomponent select > Control Panel > Add/Remove Programs > Add/Remove Windows Components > Select Details of 'Network Services' > Uncheck 'Rip Listener'. OK your way out and the component will be removed. After a short while, processes will return to normal and the PC will once again establish communications with the Endpoint server.
I hope this helps.
Lance