Startup Disk Full

A sign popped up that says that the start up disc is full and that we need to get rid of some folders.

Any folders ... all folders? Is there a limit on folders?

Answer

You certainly do not want to remove items if you do not know what they are. If the computer requires your password to move the files to the trash, it's likely you are attempting to trash required system files.

You'll want to focus on the areas you are familiar with such as iTunes, iPhoto, your Desktop and Documents folders or perhaps you email. Whereever you suspect you might have a lot of stuff.

There are are many tools that can help you determine what is taking up so much space. One of my favorites is Space Gremlin - available in the Mac App Store for $4.99 US. It provides a very nice visual representation and even allows you to delete right from the app.