Using systemd and plymouth-gdm unit instead of gdm splash screen never stops.
plymouth-quit-wait.service - Wait for Plymouth Boot Screen to Quit
Loaded: loaded (/usr/lib/systemd/system/plymouth-quit-wait.service; static)
Active: failed (Result: timeout) since Thu 2013-06-20 18:42:04 CEST; 1min 45s ago
Main PID: 449
Jun 20 18:42:04 systemd: plymouth-quit-wait.service operation timed out. Terminating.
Jun 20 18:42:04 systemd: Failed to start Wait for Plymouth Boot Screen to Quit.
Jun 20 18:42:04 systemd: Unit plymouth-quit-wait.service entered failed state.
I tried to stop it manually with the same command as the unit from command line and it worked.
*** This bug has been marked as a duplicate of bug 73585 ***