%1 (%2) %3A bad page link (error %4) has been detected in a B-Tree (ObjectId: %5, PgnoRoot: %6) of database %7 (%8 => %9, %10).

This Error event indicates that a corrupt page link was detected in a B-Tree. Available space in the Exchange store database is in the form of a list of pages that can be used to store new data. The available space is called a space tree. The space tree is held as a binary tree that is searched whenever a block of new data needs to be added to the database.

During an online defragmentation, a problem was discovered in this tree.

This event is often caused by a hardware failure or antivirus software scanning of the database file directory.

To resolve this error, do one or more of the following:

• Restore the database from backup. A bad page link error signifies logical corruption at the ESE level in the database, and it is not safe to continue using the database. The restore must be performed using a backup that was taken before this error occurred.

• If you do not have a backup that was taken before the error occurred, try to repair the database. For example, you can perform a hard repair, run isinteg -fix, and then use ExMerge on the database. If you need help repairing a database, or if the problems persist, contact Microsoft Product Support. For more information, visit the Contact Us page of the Microsoft Help and Support Web site.

• Make sure that you have properly configured your antivirus software. For more information, see the Microsoft Knowledge Base article 328841, Exchange and antivirus software.

If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.