10.7.x to 10.8.2 upgrade now Mac reboots itself...


I am having a problem with a newer mac mini that I have. I upgraded to 10.8.2 and now the mac mini reboots itself at least once a day or every other day. Sometimes it does it when I am just sitting there doing something and others time I will switch over to my PC (KVM Switch) and come back later and find it rebooted as well.

I have also noticed that since I upgraded I can't stop my Calendar from opening every time the mac starts up.

Any ideas?
The restarting sounds like potentially a power issue. I would try resetting the SMC. Google SMC reset to find Apple's help page for doing this. As for your calendar, if its open when you shut down, then by default it will open when you start up. You can change this by unchecking the related checkbox in the dialog when you restart or shut down. If not, make sure Calendar isn't for some reason in your Login Items in the Users & Groups pane of System Preferences.