Wilbur, suggest turning steam off via msconfig. If you want play via steam, just doubleclick the icon (I have it turned off by default on my machine). To get to msconfig,
Click on the orb, type msconfig, go into startup, find steam and remove the check mark in the box to the right of it. You may well be prompted to restart your computer once you apply and ok out of msconfig.
Not sure why starting task manager would cause AH to crash, doesn't make much sense, will test if on mine to see if I can replicate.
Wurz
Edit - tested, and it instadowns AH, which is interesting. Doing some digging.