I'm sorry you haven't received a reply, but as this is a fairly obscure problem, most techs working this section wouldn't know where to begin to look. I've been googling for a bit, and can't find much info on PC COE from HP, other than the fact it's a management system for updates and reliability tracking. That being said, I'm sure there are ways to find and remove the components.
Do you have OpenView installed? From what I could find, it seems to be related to OpenView. If it's there, that may give you more avenues of research.
HijackThis does not show all loading points, so not seeing anything PC COE related isn't a complete indication that there isn't something calling it there. I'm unsure which route to take from here on out, because I am unfamiliar with the service.
This does give a clue though:
"However, every 15 minutes or so I get a RUNDLL error message: "Error loading C:\PROGRA~1\HEWLET~1\PCCOE~1\reltrksi.dll The specified module could not be found."
If you are familiar with dependancy walkers, You may want to look at explorer, svchost, and rundll processes and see what's loaded under them. If you've removed all traces of the service, and it isn't loaded, there may still be references left over. At this point, I'm not entirely sure we can find out without going through some more robust logs. Those logs are only being analyzed in the Malware Removal forum. If that's the way to go, you have to be aware that there are delays in that forum due to the sheer number of topics posted daily. No topic posted there goes unanswered, but the delays can be quite long. Just telling you so you know what to expect. The delays aren't set in stone, but a longer one can be a possibility.
A shot in the dark, have you considered trying Revo Uninstaller
? Not sure if it would help, but it might... be worth trying anyway.
Let us know if the malware removal process
would be of interest for you. I can't guarantee that this is the way to go, but it might yield more clues as to what's calling the service. If you do decide to go that route, please link to this topic so the tech handling the problem has access to this information.