server event log (system) error message

i am junior administrator in school, i find that in the event log there are two error alway occur one is
(the jetdatabase call returned the following errors: -510)
event ID is 1014
the other one is
(The DHCP server encountered the following error when backing up the userdatadase)
event ID is 1016
these two alway happen at same time and happen very frequently at night time
some time will occur error
(the DHCP server encountered the following error when cleaning up the user database)
event ID is 1010
i really want to know what happen in my school’s server would some domain administrator teach me how to slove these error i mean what the errors meaning and how to stop that errors happen again.
thank you a lot !!!!!!!!!!!!!