SP2010: Internal server error–500 on My Sites web application

Problem:
This customer would try and browse to their My Site web application but would receive the dreaded 500 - Internal Server error:

From my experience, right off the bat I know this is usually a web.config problem. I was given a clue by the customer that this happened during a time when some of the admins were playing around with the installation of some 3rd party web parts in this environment. My hunch was that something got written to the web.config for this web app because when I looked at Central Admin, I noticed that they had deployed these custom web parts to ALL web applications including My Sites. So the moral of the story is to be selective when deploying web parts and only install them on the web applications that need them.

Resolution:
Since this My Site web application was pretty clean, meaning no customizations were MEANT to have been installed on it, I figured the quickest thing would be to:

Create a blank dummy web application
Copy that web.config file from that web application to the My Site web application (of course backup the existing web.config file first)