Same issue; after using 360 version 20.3.1.22 for 15 months, suddenly the icon disappears from active task tray and clicking on the program or shortcut doesn't open the GUI. ccSvcHst.exe is running...warning error 8504, 104 appears. I've already followed the three steps suggested; Power eraser, uninstalling malwarebytes antimalware and superantispyware, although for 15 months they didn't cause a problem (they were disabled unless I was running scans with them; which I was recently, but disabled again.) I'm running XP Home SP3. Chat with Norton doesn't help. Their log me in for remote actually doesn't set up completely and they aren't able to view remotely.
When I reinstall 360, I'm able to do full scan, live update, run complete backup...it works. Then I do a restart, and 360 doesn't show and cannot be opened.
Thanks for any ideas!
:smileysad:pdoyle
[edit: Clarified subject.]