We eventually got it stop by loading the COM server into the DCOM editor - the settings looked OK but we reapplied them - and then resetting IIS. Not sure the DCOM step was necessary, but after the IIS reset, it stopped adding process, began responding to web hits, and in fact started unloading them until we got back down to the 2 that were specified. But then we tried rebooting and it started all over again.
The logs show numerous instances of Events 5009 (process terminated unexpectedly) and 5011 (fatal communications error with the Windows Process Activation Service) - all associated with the WW WebConnection application pool.
Any idea what could be causing this on every reboot?
--stein