The diagnostic didn't find any problems.
Checking Computer Management/Event View/Application log I discovered som errors, avrg. 3 by a boot, mainly concerning COM+, errors that wasn't there until the day I made clon of my sys HD to a new HD device.
There was no HD r/w and cpu overload from Comodo before this date, so I don't know what came first.
My "old" sys HD is still connected, I can hear its activity during the booting, but after win is started and running there is only the sound of the new HD operation.
I plan to disconnect the old HD, but I don't think sys drive swap is the reason. It can be coincidental.