This is normal
cron has to be authenticated to the system just like everyone else and cron checks the config files to see if anything has changed. Since cron can run at any minute of the day you will see alot of them.
The first line of each is when cron starts (session open)
the second line is when cron closes (session close)
Please do not post on the same issue multiple times
it will not get you helped any faster. If there is someone one that knows the answer then they will most likely post but if no one currently on then posting multiple times will only get you talked to about it. It is against the LQ rules that you agreed to when you created an account.