Veritas NT Lock out

I am running veritas backup exec 8.5 on a NT box. I backup 1 remote server from this server. The account locks at different points when backing up mailboxes on the remote server. I use a spesific account with administrator rights to run the backup but this account locks every morning unforunately I can not pinpoint the exact process that lock the account through the event viewer. The solutions given on the veritas site does not solve the problem. Is there a way to set an account that it does not lock within NT no matter what.