SAS fails to start. What do I do?

Error: Invalid physical name for library SASUSER
Note: Unable to initialize the options subsystem.
Error: (SASXKINI): PHASE 3 KERNEL INITIALIZATION FAILED.
Error: Unable to initialize the SAS kernel.

Solution: Oddly enough, this means your quota for Documents/Desktop folders is full. That limit is 500MB by default, and includes the Recycle Bin. Move items from these locations to your Project Workspace or delete them (and empty the trash) then relaunch SAS and it should work.