Every few minutes I get a message like "Can't save temporary files." I can't continue editing until I cancel it. It does not seem to affect the system. I can still save, and save as.

Does the system have to save temporary files? If so, what should I do?

Sounds like you are not running the editor as an administrator so it can make changes to the drive.

what Operating System are you using?

Are you saving to the programs directory? You shouldn't.