A couple of days ago my Linux Mint suddenly didn't shut down any more - just hangs at some point - and I had to use the magic sysrequest to orderly shut down the system. In addition I noticed the system began to start, but didn't finally finish to boot. First of all I thought it's some hardware which fails to work. I unplugged all external hardware but the problem didn't vanish. I crossed the fingers it's not a HW issue of my system itself like a memory issue, SSD issue or similar. So I thought it's most probably an issue of the Linux OS. Then I searched the net for hints how detect the root cause and finally found 

systemctl --failed

which told me there are two failed services:

1) casper-md5check

2) vmware

I then disabled and uninstalled both and now my system starts and stops again like a charm. I already noticed the vmware workstation didn't start because of some build errors but I didn't expect this to be the root cause of tmy issue. Not sure whether this was the root cause or md5check. But in any case - this command helped me to locate and solve the root cause of my problem.