There are 3 possible resolutions to this problem:
Microsoft recommends performing a DBCC CHECKDB command on the database to attempt to repair the database.
This procedure is explained in the following articles: http://support.microsoft.com/kb/828339
If errors are found and repaired, attempt the migration again.
Restore a previous version of the database before the corruption occurred and attempt the migration.
Check the DB system for failed hardware, usually a hard drive or disk controller, replace the failed hardware.