FYI, that last Bitdefender update was the *cause* of the DPC Watchdog Violations

I saw a few other people with similar problems, including a few not realizing the issue was caused by Bitdefender, and another post about BCCI.Sys.  However, not everyone was fortunate enough to get a specific driver name during their diagnostics, in my case it was DPC Watchdog Violations within moments of signing into my computer account.  (Booting to the logon screen worked quite well, although even from there there were boot cycles going on too.)

FYI, it was that last Bitdefender update, in my case it applied Saturday Nov 18th early a.m. on two of my computers.  I lost a day of my life, because in my case, it was a blue screen, and no driver name in the diagnostics, it took a while to eventually pinpoint Bitdefender as the culprit.  In my case, the computer blue-screened within moments, occasionally a few minutes of signing in.  I had to go into safe mode, and run a lot of diagnostics.  Eventually, I noticed the date of the bitdefender driver. 

To fix, I had to download bitdefender uninstall in safe mode, run it, and once I did that, both computers, all is fine.  I'm on WIndows Defender for the moment.  

I've been very happy with Bitdefender for about 4 years, I hope you will patch that, work on your QA processes, and hopefully it won't happen again.