Don't know if you ever had that guys,
First time I'm seeing it and do not really understand:
I was working a PSB file of 1,42 giga and when I wanted to save one of the multiple layers I added, PS told me that my scratches disks where full (and they are of course not)
"Save as" in any different HDs couldn't solve anything and had to close the application without saving.
When I re-opened it, I had this message: "could not open a scratch file because the file is locked. use the properties command in the windows explorer to unlock the file".
So I can't launch PS CS4 again. (not that I can't re-open the PSB, I simply can't access again to Photoshop CS4 and got this message)
Tried to open in CS3, no problem, works perfectly.
Thanks for your help