I'm at a loss for what's going on here; I've changed the font a couple
of times, but can't get it to change anymore:

Debugger entered--Lisp error: (error "Invalid font name" "-Misc-Fixed-normal-normal-semi-condensed-*-12-*-*-*-c-60-iso10646-1")
  internal-set-lisp-face-attribute(default :width normal #<frame emacs@hydrogen 0x98c7a50>)
  set-face-attribute(default #<frame emacs@hydrogen 0x98c7a50> :width normal :weight normal :slant normal :font "6x10")
  set-frame-font("6x10" nil t)
  eval((set-frame-font "6x10" nil t) nil)
  eval-last-sexp-1(nil)
  eval-last-sexp(nil)
  call-interactively(eval-last-sexp record nil)
  command-execute(eval-last-sexp record)
  execute-extended-command(nil "eval-last-sexp")
  call-interactively(execute-extended-command nil nil)