What may have hapenned is that your password store has become corrupt one way or the other.
Exit out of the Backup Exec Administration Console
Type :BESTOP to halt Veritas Backup Exec at the NetWare Console
Map a drive to SYS:\BKUPEXEC\JOBDATA
Rename the two files used for the User Password Database
userpass.dat and userpass.idx
Type :BESTART at the NetWare server Console
After that you'll have to edit all your jobs to enter new passwords for each of them.