This looks as if something isn't installing properly. What McAfee installation have you got? And have you run MVT to check that everything is installed?
But what does it says? The reason for restarting? Maybe there is some unresolved problem, malware that it can't remove?
Can you please navigate to C:\Program Files\Mozilla Firefox\Components and rename the file Scriptff.dll to Scriptffold.dll and restart the PC. The abnormal restart promt shouldn’t occur then.
This fixed the issue as of today.
Thank you, JaiPrakash!
Glad that you are OK now, please do report back if any issues. . .