Is there any way to automatically close filename completetion buffers in Emacs?

Question

For example, when you open a file via C-x-C-f, you can TAB complete file names, and if there are more than one possible completions, it will pop open a completion buffer with a

Answer 1

Although it does not directly solve your problem have you considered ido-mode as a mechanism for opening files?

ido-mode will bind C-x C-f to ido-find-file this allows you to interactively opening files (selecting between name collisions from within the minibuffer C-s and various other nifty features) I find it a much easier method of finding files and it will get rid of the *Completions* buffer altogether.