Sorry for the trouble. I'm completely guessing here, but considering:
1. HFS+ is a steaming pile of fail.
2. You're apparently using an external hard drive (see point #1) for media storage.
I'm guessing there are filesystem errors on one or more of your disks.
Please see:
http://wiki.jriver.com/index.php/Troubleshooting_DisksRun through the Filesystem Corruption fix described for both your internal system disk and the external media disk (the external one will be easier to do because you won't have to reboot your Mac to do it).
If that doesn't get you going, we'll need more detail on exactly what happened, as your initial description was a bit vague. Did it crash when you were trying to get the Media Network key? How did it close? Is the stuff on the drive accessible? And so on and so forth.