Disk is full error

I had an external disk drive that appeared to be starting to fail, so I bought a new one and copied all of the files from the old drive onto the new drive.  Now Adobe Photoshop 7 will not save anything because it says the disk drive is full.  I have over 5 terrabytes open on both the old and the new drive.  I eventually uninstalled and reinstalled Adobe Photoshop, but it still has the same error message.  Any help you can provide will be greatly appreciated.