Microsoft Exchange Server, like any software that is database related, requires constant attention in order to insure that the database stays in a consistent state.
In order to insure that your database is operating in a consistent state check the event log. If there are PAGE ERRORS, READ VERIFACTION FAILURES and INVALID TABLES these problem causing errors are usually logged in the event log.

Some common causes of errors developing in the database are:

1)Mailboxes have been removed but the data still occupies pages
2)The disks I/O is too slow for the number of transactions happening
3)The database is outgrowing the amount of available hard drive space

To keep from having these problems you can do the following:

1)De fragment your database every month
2) Make sure you have your log files and database files on a separate hard drive
3)A separate hard drive is not a separate partition but rather another physical disk or 4)RAID configuration that is on its own controller.

NOTE: Make sure you check the integrity of your backups!

Backing up the database of course is the most efficient way of insuring that when a disaster does occur your company will have minimal down time and minimal data loss. There are two methods of backing up your database. The two options are, to use an Exchange Agent, or perform an Offline Backup.

If you use an Exchange Agent, you can backup your database without interrupting mail transfer. Exchange Agents work through Exchange Server. With Exchange 2000 - 2003 you can use NTBACKUP.

If you want to perform an Offline backup you must first shutdown the Information Store service (Exchange Server 5.5) or dismount the databases. (Exchange Server 2000 - 2003)

REMEMBER: to backup your priv.edb priv1.edb pub.edb pub1.edb stm & log Files prior to running any type of Exchange utility on your corrupt Exchange Server Database.