what hjt is telling you is simply that it can't find the file that the service points to (which can simply mean that it couldn't get access, hence the suggestion to run as administrator). I originally assumed that there was a reason you were looking at those specifically.
If both hjt and mwb are showing clean, it's probably not malware related.
cpu spikes can be caused by a number of things. Get rid of addons you don't use in ff. uninstall unnecessary and unwanted software, run ccleaner... general optimization kinda stuff. If you want to see what's causing the spikes, watch task manager and sort by CPU. It'll tell you what's using the resources.
Edit: started typing before your last post. "Startup Control" is much more comprehensive than ccleaners startup tool.