Yea I'm having the same issue. Not a Windows 8 issue, I have Windows 7... It's the ~mnn133.tmp file that the trainer creates. Bitdefender is seeing it as a Trojan Generic 14559347 virus and is blocking it. It doesn't seem to matter if you added an exclusion for the trainer or not. The trainer was working fine yesterday. Something must have happened during a Bitdefender update last night/earlier today for this to be happening.
Funny thing...AVG which 0x90 recommended last year...is also having issues with the same ~mnn133.tmp file. What's up with that?