10.6.3 is Definitely bugged

[Boesky]

I log back onto my Mac only to see all my programs closing and then being kicked off of my account, only to log back in as if I restarted my computer. Another time, I logged back in onto my Mac only to see all my programs were closed and it was as if I restarted the computer.

 

[calderone]

Check here:

 

[Arrandale]

Check here:

sounds like your issue

other users are reporting extreme sluggishness and poor wireless reception