how do I find out what's hanging me up?

Hi all,
The short version of a long story.  I've just installed sonar on a dell pc.  I've also got it installed on a compaq/hp machine, where the followig
problem doesn't exist.  On the dell, sudo reboot seems to hang.  Sudo shutdown works fine.  I've tried sudo shutdown -r now, sudo systemctl reboot, and
other options.  How, without sighted help, can I find out what's causing this machine to hang when I reboot.  What's strange is this...why does it shut
down just fine, but not reboot?

Mark Peveto
Registered Linux user number 600552
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