Could not complete your request because scratch disks are full-Photoshop error

I am trying to open files in photoshop but can't do so . Everytime I try to open a new file it gives error that
Could not complete your request because scratch disks are full

I have attached its page shot. My laptop has 2 GB ram and hard drive is 100 GB free . What is scratch disk to which this error is showing ?

Goto Start --> Run

And type following :

Code:

---

%TEMP%

---

It will open a folder with lots of files, delete all those files and start your photoshop again. If that doesn't helps then let us know.