Logshipping --SQLserver2005-- not a valid Microsoft Tape Format backup set

Hello,
 I have log shipping running for a while  but today I getting the error below. How do I fix this issue.

Message
2011-03-01 09:15:08.18      Starting transaction log restore. Secondary ID: '112ad7af-0593-47b3-9e88-72443f75cbc2'
2011-03-01 09:15:08.19      Retrieving restore settings. Secondary ID: '112ad7af-0593-47b3-9e88-72443f75cbc2'
2011-03-01 09:15:08.19      Retrieved common restore settings. Primary Server: 'GRATWA01', Primary Database: 'osv_projects_hipath8k_v4_0_db', Backup Destination Directory: 'F:\logshipping\hipath8k_v4_0', File Retention Period: 43200 minute(s)
2011-03-01 09:15:08.19      Retrieved database restore settings. Secondary Database: 'osv_projects_hipath8k_v4_0_db', Restore Delay: 0, Restore All: True, Restore Mode: Standby, Disconnect Users: True, Last Restored File: F:\logshipping\hipath8k_v4_0\osv_projects_hipath8k_v4_0_db_20110228190010.trn, Block Size: Not Specified, Buffer Count: Not Specified, Max Transfer Size: Not Specified

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2011-03-01 09:15:08.43      *** Error: Could not apply log backup file 'F:\logshipping\hipath8k_v4_0\osv_projects_hipath8k_v4_0_db_20110228223011.trn' to secondary database 'osv_projects_hipath8k_v4_0_db'.(Microsoft.SqlServer.Management.LogShipping) ***
2011-03-01 09:15:08.43      *** Error: The file on device 'F:\logshipping\hipath8k_v4_0\osv_projects_hipath8k_v4_0_db_20110228223011.trn' is not a valid Microsoft Tape Format backup set.
RESTORE LOG is terminating abnormally.(.Net SqlClient Data Provider) ***