PS CS4 scratch disk full?

here are 2 SH of my problem that pretty much add it up. Please help and explain what this is.

[IMG]http://i869.photobucke*****m/albums/ab256/ansuzhfoe/untitled2.jpg[/IMG]

And this pops if i click or tap a key on my mouse/keyboard.

[IMG]http://i869.photobucke*****m/albums/ab256/ansuzhfoe/untitled.jpg[/IMG]

I've already posted in Hardware/Software help section. But, that section is dead.

When your system does not have enough RAM to perform an operation, Photoshop uses a proprietary virtual memory technology, also called scratch disks. A scratch disk is any drive or drive partition with free memory. By default, Photoshop uses the hard drive on which the operating system is installed as the primary scratch disk.