Scratch Disk Full

Hi there, 

Photoshop is tell me "scratch disks full". My mac has a nice bit of room free (160 GB). It has a 2.5 GHz Intel Core i7 processor and16 GB 2133 MHz LPDDR3 memory. I have looked at other posts and have tried adjusting the preference etc. but have had no luck.

Any help would be great 🙂 

Thanks!