Windows admin account blocked by CIS

I had been running CIS (free version) last year on my Windows 8 System until one day when I logged in I couldnt see any of my installed program neither I was able to do anything at all (Very much like user blocked from accessing system).

On system start up, I could log in but after logged in I was blocked from accessing my system. At first I didnt know it was caused by CIS and was very panicked. Than I boot in Safe Mode (disabling any startup program) and I wasnt blocked anymore. I uninstalled CIS while in Safe Mode and than logged in again in Normal Mode. Surprisingly problem was solved. After that I have been running some other antivirus for about a year now.

There are no malware on my system because every month I scan my system with Avira, Malwarebytes, Hitman pro and kaspersky Security Scan and I have not found anything. And my computer has only one admin account.

I have been missing advanced feature provided by CIS like firewall and sandbox etc… And I have been thinking to install CIS again.
But I am worried if something similar happen again, So does anyone know what might have happened and If I could avoid happening similar in future?

p.s. Unfortunately I cant provide log files. sorry about that.