Failure on large database backup

Hello-

I have a 460 GB database I am trying to (full) back up to another server. the job has failed twice; here is the log entry:

SQL Backup log file 5.2.0.2825
11/27/2007 4:54:18 PM: Backing up ServicingODS (full database) on COREPROD instance to:
11/27/2007 4:54:18 PM: \\mtgsmneg036\SQLBackup\Full\ServicingODS\FULL_COREPROD_ServicingODS_20071127_165418.sqb

11/27/2007 4:54:18 PM: BACKUP DATABASE [ServicingODS] TO DISK = '\\mtgsmneg036\SQLBackup\Full\ServicingODS\<AUTO>.sqb' WITH NAME = '<AUTO>', DESCRIPTION = '<AUTO>', INIT, VERIFY, COMPRESSION = 1

11/27/2007 4:57:59 PM: Thread 0 error:
Error 620: Error writing to backup file(s).
Process terminated unexpectedly. Error code: -2139684860
11/27/2007 4:57:59 PM: Warning 210: Thread 0 warning:
Warning 210: Error writing to backup file: \\mtgsmneg036\SQLBackup\Full\ServicingODS\FULL_COREPROD_ServicingODS_20071127_165418.sqb
Warning: System error 121 (The semaphore timeout period has expired)

SQL error 3013: SQL error 3013: BACKUP DATABASE is terminating abnormally.
SQL error 3271: SQL error 3271: A nonrecoverable I/O error occurred on file "SQLBACKUP_420A8872-5D92-4DBB-884D-62149895816D:" 995(The I/O operation has been aborted because of either a thread exit or an application request.).
SQL error 3202: SQL error 3202: Write on "SQLBACKUP_420A8872-5D92-4DBB-884D-62149895816D" failed: 1117(The request could not be performed because of an I/O device error.)

Any help is greatly appreciated. Full backups of smaller db's seem to work fine...

Thanks!

Jason