Why we have to restart the J2EE engine???

Hi all,

every 5 days all the messages are sitting in adapter engine as status ''TO BE DELIVERED''. everytime after restarting the J2EE engine all the messages came up with ''successfull''. its happening in our Production System.

1)why this problem is happenning every 5 days?

2)after restarting the J2EE engine why all the messages gone through sucessfull?

3) is there any altternative way to fix this problem without restaring the J2ee engine?

Answer will be rewarded.

Kiran.