Get the APE off your back and overcome the Leopard "blue screen" startup hang

You've installed Leopard and gotten the "Install Successful" screen, but on the first (and after every following and increasingly frustrating) startup attempt, all you get is a little hard drive activity and a blank blue screen with the mouse cursor in the upper left corner -- not quite a blue screen of death, more of a blue screen of chemically-induced coma, but just as annoying.

This is probably a fairly simple startup problem and not a my-entire-system-just-ate-itself install problem, so don't freak out just yet. Remember all those cool Unsanity haxies you installed back in the day?  They might not be playing so well with Leopard.  Basically, you need to get rid of the Application Enhancer (APE), but that's hard to do when your machine is stuck in an unresponsive haze.

The fix I used comes from here.  If you follow the link, the instructions are a little more detailed.  The long and short of it is this:  

1) Find a working Mac with a firewire port.

2) Connect the working Mac to your Mac via firewire (If your Mac doesn't have firewire I have no idea how to help you).

3) Restart your Mac in firewire target-disk mode (hold down T while starting up).

4) Using the working Mac, find the following files on your Mac and pull them to the trash.

/Library/Preference Panes/Application Enhancer.prefpane

/Library/Frameworks/Application Enhancer.framework

/System/Library/SystemConfiguration/Application Enhancer.bundle

/Library/Preferences/com.unsanity.ape.plist

5) Empty the trash and unmount the firewire drive for your Mac on the working Mac.

6) Unplug the firewire cable and restart your Mac.

7) Everything should be fine.

This worked for me, but your mileage may vary if you have other haxies installed.  Check out the compatibility list from Unsanity for more info.  Good luck.

UPDATE:

If you are a l33t h4x0r, you can do this:

1)  Boot your Mac into single user mode (hold down command-s while starting up)

2)  Get into the Terminal and delete the following using these commands:

rm -rf /Library/Preference Panes/Application Enhancer.prefpane

rm -rf /Library/Frameworks/ApplicationEnhancer.framework

rm -rf /System/Library/SystemConfiguration/Application[no space here, it's just that my blogger formatting sucks]Enhancer.bundle

rm -rf /Library/Preferences/com.unsanity.ape.plist

3) Restart

Use these at your own risk.  If you don't know what you are doing with the command line, don't do anything with the command line.

Good luck.