So, as I also had this "Scratch disk Full" error with PhotoShop 7 on Windows10-64bit yesterday, and ALL the given solutions are NOT working, here is mine that works: The problem isn´t in the presence of a "drive bigger than 1TB", it is due to "drive with more than 1 TB free of space" ! So just make an i.e. \TEMP2 folder on that concerning harddrive, and fill it up with some stuff until the free space is less than ca. 950 GB. That´s it. Works like a charm for me.
