Spooler simply stops every time you try to print or add a printer or something? You can keep restarting it but will never be able to print something? I won’t pretend to know your problem since it depends on potentially so many things but if you have a MacBook, one thing worth investigating is have you been running VMWare Fusion? The ThinPrint drivers of the VMWare Tools seem to be able to cause this problem when you run the same machine in BootCamp mode. Unfortunately, you can’t just uninstall it. Uninstalling VMWare Tools from inside virtual mode seems to solve this problem