Won't let me open or start a new file.

I went to go open up a file and it wouldn't let me, kept on saying "Could not complete the open command because too many files were selected for opening at once" when I was trying to open ONE file. I also tried to start a new file and got this: "Could not create a new document because there are too many files open. Try closing some windows and try again" I literally have ONE window open. I'm assuming it's a bug or a glitch? This has been happening every now and then and it's ridiculous especially considering that I pay for this every single month.