My mini won't shut down

Question

when i try to shut down my mini, it keeps running. it gets to the point of logging out and i can see just the plain desktop picture. the fan is going, the monitor is on. it won't actually turn off. i've waited for 30 minutes. finally, i'll just unplug it (probably not good.)
any suggestions?
thank you.

Answer 1

Usually if the system refuses to shut down it's because a process is running that it can't force-quit, often related to an external device, but sometimes an installed application attempting to communicate.
Often the only way to resolve this is to power down by pressing and holding the power button for 5-10 seconds. This is not an elegant shutdown, particularly if the system is attempting to write to the hard drive in the hung activity, so on the next reboot, it is wise to run Disk Utility to verify the internal hard drive and ensure it hasn't developed a problem.
There's no simple way to troubleshoot this sort of problem since the devices connected to the system and the software in use all vary from system to system, but it's best to start by disconnecting all external devices other than keyboard mouse and screen and booting the system, then trying to shut down again before running any application. If that works fine, then it's a problem in an app or driver or external device. If not, it's in MacOS or hardware.
If the latter, it's probably a good starting point to repair permissions using Disk Utility, though sometimes a little more drastic spring-cleaning is needed using one of the general purpose utilities such as OnyX or YASU (YASU being my favorite for simplicity of use and the lack of options that can do more harm than good). Running all YASU tasks can help a range of behavioral problems. Another good utility to have on hand for these type of problems is Preferential Treatment, which can be run on both system and user levels to find damaged or corrupt properly list (plist) files which can also cause unpredictable behavior.
If the former, then it would help to know what devices and software you are using, but troubleshooting would typically need each to be connected/used individually to see at what point the system then began to have problems again.