now() time off

[John McCawley <nospam@xxxxxxxxxxxx>]

Earlier this week when I logged into my database, I just so happened to 
notice that the value for now() was six hours off of the time reported 
by the operating system when using the date command from the command 
line.  How is this possible?  I rebooted the server and the problem 
magically went away.  I am quite certain that I didn't modify anything 
in the database that should cause this problem.  It turns out that that 
the now() time has been off for some time, and resulted in quite a bit 
of corrupted data.  What exactly should I do in the future to keep this 
from happening, or where should I look for clues?

John