Why can't I switch virtual terminal now?

I have noticed I can't lock the screen because of vlock hangs. chvt also hangs on VT_WAITACTIVE and only attempts to switch the terminal (I see the image blinking). Pressing keys that in usually switches VT in text mode (Alt+arrows, Alt+Fx) also makes Xorg picture blink and hide cursor for a second. The keyboard input also flows to text console in addition to Xorg. I noticed a stray session at tty2. I can log in to tty2 without leaving Xorg: # ps aux | grep qwjerewqr vi 27051 0.0 0.0 3644 1144 tty2 S+ 20:38 0:00 grep qwjerewqr root 27053 0.0 0.0 3644 1236 pts/27 SN+ 20:38 0:00 grep qwjerewqr So, 1. What may have caused this? 2. How do I bring the system back to normal without rebooting (or restarting X applications)? 3. Shall I report a bug report somewhere? Update: Finally just rebooted it (because of other unrelated problem).