This is happening when I try to start the installer. Regardless of what hard drive the installer is on I get the same message. Was planning to use a different drive as scratch disk when I've completed the install but I can't even start the *.exe 🙂
Installers need a good deal of space on C, for temporary files and common files, even if you get the chance to install the app somewhere else. There is a fashion among PC makers of giving a tiny C drive, but it's a disaster.