I don't know - you would have to take that up with them, but continued use could cause the same problem.
I occasionally use the free version of MBAM for any additional scans which doesn't cause any problems.
I think it was a couple of years back that I ran a scan with Combofix and it took out a system file for which there were a number of complaints on their forum.
Fortunately because I create regular system images, I was able to restore my system.
I once read that Combofix should be used under supervision - usually the supervision of an antimalware helper, probably because of its aggressiveness.
It would be my advice to stop using it.