The scripts located in /etc/init.d are part of the bootup sequence of every Debian-like distro. Very often Ubuntu's documentation and guides have suggested - in order to deactivate init scripts - to change the permissions of the scripts in /etc/init.d, making them non-executable. This will have the following consequences:

• You'll get an error message at boot time (to avoid it you need to patch all the scripts);
• You are breaking the logical chain stated in debian-policy concerning runlevel configuration.

If the logic of a debian-like system boot up sequence is not very clear and familiar to you, you should not play with symlinks, permissions, etc. In order to avoid messing up your system, Boot-Up Manager will automate all of your configuration in a nice and clean graphical interface.