Please don't install this hack (versions 0.1 and 0.2), it will disable copying files over USB storage and as a result installing any hacks or updates (UPDATE ERROR: 3).
I didn't find out because I don't use the USB connection at all, I use sftp over Wi-Fi instead. Sorry for any inconvenience.
If you already did install it, here's how to get rid of it and make the user store usable again:
- Delete the whole directory 'freedownload' in user store
- Restart your Kindle
- Copy appropriate update_freedownload_0.*_k3*_uninstall.bin to user store then go to Settings and select 'Update your Kindle' in the menu.
- Restart the Kindle again
- Now your Kindle's user store should be OK again, you can check the filesystem for errors from your PC to make sure everything is all right