Ubuntu has an application called Computer Janitor. It's found under System » Administration » Computer Janitor. The concept is that when you have installed files and dependencies that are no longer needed or being used the application will make you aware that they exist and one could save disk space by getting rid of them. It seems like a great idea, but is there a catch?
There are some problems with this application that one should be aware of. Generally when you get these tools shipped with Ubuntu, they normally do not have any strange effects on your system but this one does. The heart of the application is right but real world usage can be a problem.
Say for example that you have installed a debian package from another site that is not in the repositories. Computer Janitor tends to let users know that these aren't being used and need to be removed from the system. The reality is that these packages are applications that you are currently using. The way to get around this is to uncheck them from being removed each time you run the program.
The end results of removing the packages Computer Janitor asks you to remove is not that great. The reason is that many of these are very small packages that are only a could kilobytes in size. For most it's trivial whether these remain on the system or not.
For the time being until something is upgraded, it's a good idea to avoid using this program just in case.
