Black screen after resume?

I have an Asus laptop (Cr400) running Mint 17.1. If the machine is put into sleep and then resumed, I get a black screen. I can use Ctrl-Opt-F1 to switch to a command line, but that hangs at a flashing cursor before asking for a password. Switching back to F7 gives a flashing cursor. I can no longer SSH into the machine. Is there a solution?