McAfee Support are finding one Fixit invaluable at fixing a problem where 3rd party software firewalls wont start due to WFS and BFE services not starting as they should, a clash between some unknown Windows Update and the software, they are still working on it apparently. So I know of several instances where it has worked.
I agree however, most of them don't seem to fix, or only temporarily fix the situations.
I have about an 80/20 success rate with Fixits. 20 percent success. When it works, it works well, when it doesn't work, it doesn't work at all. The System has improved over time. Right now, my PC is still suffering random full freezes. my system was up for 96 hours this last time, which was the longest it has gone without a freeze. I just can't seem to find why it is happening.