Why does the computer freeze when I unplug the headphones

Could you try creating a new user and see if it happens there? Create a new user. Restart your computer and log with the new user. Make sure you don’t have anything in the “Login Items” (nothing starts at login).

Also try starting your Mac in “Safe Mode” as described here and see how it goes.

This could be related to a Kernel Extension (ktext) problem.

First of all, I'll address the how to uninstall Soundflower problem:

A number of people have run into problems uninstalling it in the past. The main problem seems to be that you have to reboot your machine after running the uninstaller but if that doesn't work for you try removing it from the Audio MIDI setup.

Open Audio MIDI Setup in the utilities folder and look for Soundflower listed there, select it and click the minus near the bottom left to remove it.

Now that you've removed Soundflower, you need to set the headphones as your default output device:

1. Connect your headphones
2. Open System Preferences and Open the "Sound" panel
3. Go to the "Output" tab
4. Select your headphones here
5. Close system preferences

Your system should now default to the headphones whenever you plug them in.

If you run into further problems, you can try a couple of advanced steps:

1. Open Finder and in the "Go" menu, select "Go to Folder..."
2. Type ~/Library/Preferences and click Go
3. Locate two files called com.apple.systempreferences.plist and com.apple.audio.AudioMIDISetup.plist and move them both to the trash
4. Reboot your computer
5. If you're still having problems reset PRAM by rebooting again and holding command-option-p-r as soon as your computer boots up, keep holding until your computer restarts again and you hear the startup chime.

Follow all the above steps from the beginning of this post and one of them should solve your problem, make sure you check each time if your headphones are now working by default.