Scratch Disk Full Error Preventing Re-installation
The Photoshop 7 scratch disk defaults to Drive C (System Drive) during a fresh installation, regardless of where you install Photoshop itself. The scratch disk free space MUST be LESS than 1 TB for it to work. If you don't want to fill up Drive C with junk to get the free space under 1 TB, then you need to change the scratch disk drive when starting up Photoshop. To do this, press Ctrl and Alt together as soon as you can after clicking the Photoshop icon to start up. This will interrupt the startup process and present a menu, where you can change your scratch disk to another drive.