By default Windows stores all the user's documents, the installed programs and the system files in the C: drive. As a result of this C: drive is the one that gets filled faster than other drives. Once the free space in C: drive (or any other drive) becomes very low, Windows starts to show the above annoying balloon pop up message. How do you solve such a problem? Just read along.
Scenario: The free space in your C: drive is in MB range while any of your other drives (D, E ...) have ample space. Since most of the programs require some space in C: during running/installing, you will find yourself unable to do your daily PC work as you would normally do, in this situation.