I do have this issue once a while but not a big problem for me as it works well most of the time.
No choice but to restart box for my case.

Means, there's something holding up its exit process. Not allowing it to quit properly.. Best way to resolve is to check the logs and do some troubleshooting, and or retrace your recent installs/config to figure out the culprit.. If not bothered, it can be left as is and most times, poses no major issues.. Other times, it'll crash that one time and then refuse to load up.. Meaning you'd have to clear data and fresh start.