Illustrator will not save file

When I go to save my illustrator file, it comes up with an error message saying "Can't save the illustration. .278." My storage on my computer is starting to get pretty low, so I thought I'd try saving it on my external hard drive to see if that worked. When I tried to do this, it came up with a different error message saying "This file cannot be found." I've done some googling and any suggestions that I've seen have not worked. I tried copying and pasting to a new file and that didn't work. From what I can tell, most of the time when people have this issue, it has something to do with text in their file, but I don't have any in mine. Anyone have any idea how to get around this? Thanks