Scratch Disk Full?

[r1zeek]

I have a Mac G4 dual running Mac OS 9 (not sure about the version but can find out) and I do most of my Photoshop work on it.

Now I have some space on my "Mackintosh HDD" (about 4Gb+ I think) and when I open up Photoshop it tells me my "Scratch disk is full" and I cannot do any photoshop work. Now I am storing all my data on an external HDD (apart from system files) but it still won't let me use Photoshop, what do I do?!?!

And By the way, i'm no Mac wizard so if you know an answer describe it easily for me!
Thanks

[EDIT: Fixed! ]

[bmh.01]

EDIT: Saw your edit.