1. The title should be helpful in finding the question when someone with a similar problem does a search.  You have a valid point that including random diagnostics in the title doesn't help and probably hinders.

 2. Putting Windows Update in the title introduces the same problem.  It presupposes the cause and may deflect people who don't recognize that a Windows update might be behind their issue.  In fact, the OP assumed that updated everything was the solution.

I would suggest something like: 

**Terrible font rendering recently in some applications but not others**