Can anyone explain what just happened?

[dance2noise002]

I was just watching a video on Youtube and then all of a sudden my entire machine freezes, and it logged out me out completely to the main login screen? There was that tiny loading rotate logo in the screen also.

What could have caused this?

 

[Eidorian]

Flash probably took the system down.

 

[TSX]

What computer do u have?

 

[dance2noise002]

It's a 2007 Mac Mini, 1GB of RAM, 1.83GHz. I was using Safari at the time of the log out.