Is it not possible to launch any part of the program? Even going to a folder and right clicking an image and choosing “Open with Photoshop Elements” or double clicking the application “PhotoshopElements” in Program Files\Adobe\Photoshop Elements
Program Files (x86) on Windows 64 bit.
It’s not clear what you can do otherwise.
Normally scratch disks are allocated through preferences e.g. in PSE2
Edit à Preferences à Plug-ins & Scratch Disks
First disk is normally allocated to start up and you need to allocate the second to the C: drive or other volume.
You can check this if you still have PSE2 working on an old machine but unless anyone else can think of a solution you may be stuck.
If you have windows 8 and you are trying to start Photoshop and you are getting this message "could not initialize PhotoShop elements because the scratch disk are full." you may be having the same problem I did. I have a 2 terabyte hard drive. It seems PhotoShop will not work in a system that has more that 1 terabyte free disk space. What I did was create a virtual hard disk big enough to allow my C drive to have less than 1 terabyte free disk space.
To do this press the windows button and c at the same time. A search screen will come up on the right side of screen. In the search space type in “create and format hard disk partitions”. Then click actions, then click create VHD, then in the locations space find your C drive. Then in the virtual hard disk space put in the amount that will allow your C drive to have a little less than 1 terabyte disk space. . In my case I put in .8. Then click VHDX. Then click fixed size. . Wait while the system creates the VGDX. This should not take long at all. Then click OK. You should be able to now use PhotoShop. I hope this helps.