--- Developper s Lair ---
Comodo had generated 6000+ entries in it's "My Pending Files" section of D+, all of which were in firefox's cache directory. The File names were highly suspicious for some sort of error, as they all had paths similar to: ".../Local Settings/Application Data/Mozilla/Firefox/Profiles/xxxxx/Cache/Cache.Trash/Cache/Cache.Trash/Cache/Cache.Trash...etc" you get the idea.
This exact issue has been plaguing me for a while now. Every time I closed Firefox & emptied the cache, cmdagent.exe would max out one of my CPU cores for up to 10 minutes. Like you, I had tried setting Firefox to Web Browser & Trusted Application status without success. Your solution worked beautifully. This is obviously a bug in what I have otherwise found to be a fine product.
