The following configuration causes a problem when trying to switch to a recently closed buffer:

(flx-ido-mode 1)
(setq ido-use-virtual-buffers 'auto)

Invoking ido-switch-buffer and then typing a name that does not match the current set of buffers but does match a recently visited buffer causes the cursor to jump to the beginning of the minibuffer (before the prompt) and gets things in a state where the only thing I can do is cancel out with C-g.