Comment 7 for bug 414689

Another test: as AlmaTlust said, if the printer is frozen (and it freezes righ after pushing the print button in any app), and you unplug the power but not USB it freezes again a few seconds after you've replugged the power cable.
But if you do the same and delete the print job (either in CUPS web interface or through the printing applet) while the power is disconnected, the printer boots fine and is responding. Then you try to print again: it might print, or it might freeze again.