Windows XP RunAs feature is horribly broken

Switching back to Windows XP from the Mac has been educational. Along with learning a lot more about Cygin than I had ever known before, I’m discovering new features-to-be-avoided in Windows XP. Here is a biggie: “Run As”.
Windows allows you to execute programs with another user’s credentials. You are probability thinking “Simple right?”. Well, it isn’t. Using this feature seems to consistently corrupt the RunAs-ed user’s profile. Corrupted profiles seem to be a mysterious thing with little to no way to fix them; creating a new profile is basically the only solution. In my case I restored from a nightly backup (because I know stuff like this is bound to happen on Windows). My takeaway:
Disable RunAs on Windows!
Here is how.