Error Writing To Backup File

We received the following error last night and were wondering if you could advise us as to the problem:

We are backing up multiple databases within one step. The first 35 backups work with no errors the last one failed with the following error:

7/9/2008 4:00:58 AM: Backing up msdb (full database) to:
7/9/2008 4:00:58 AM: I:\MSSQL\Backup\Database\FULL_DBPODS100_msdb_20080709_040058.sqb

7/9/2008 4:00:58 AM: BACKUP DATABASE [msdb] TO DISK = 'I:\MSSQL\Backup\Database\<AUTO>' WITH NAME = '<AUTO>', DESCRIPTION = '<AUTO>', ERASEFILES = 2, MAILTO_ONERROR = 'rbranch@geosolinc.com;dsharpe@Geosolinc.com', FILEOPTIONS = 1, COMPRESSION = 1

7/9/2008 4:01:02 AM: Thread 0 error:
Error 620: Error writing to backup file(s).
7/9/2008 4:01:02 AM: Warning 210: Thread 0 warning:
Warning 210: Error writing to backup file: I:\MSSQL\Backup\Database\FULL_DBPODS100_msdb_20080709_040058.sqb
Warning: System error (The parameter is incorrect)
Processed 2344 pages for database 'msdb', file 'MSDBData' on file 1.
Processed 25 pages for database 'msdb', file 'MSDBLog' on file 1.
BACKUP DATABASE successfully processed 2369 pages in 1.701 seconds (11.406 MB/sec).


We are on version 5.1.0.2781 on a AMD X64 64-bit machine The SQL Server version is 9.0.0.3042

The Job step looks as follows:
DECLARE @exitcode int
DECLARE @sqlerrorcode int
exec master..sqlbackup N'-SQL "BACKUP DATABASES EXCLUDE [XXXXXX, XXXXXXXXX]
TO DISK = ''I:\MSSQL\Backup\Database\<AUTO>''
WITH NAME = ''<AUTO>'', DESCRIPTION = ''<AUTO>'', ERASEFILES_ATSTART = 2,
MAILTO_ONERROR = ''XXXXXX@XXXXX;XXXXX@XXXXX'',
FILEOPTIONS = 1,
COMPRESSION = 1"', @exitcode OUTPUT, @sqlerrorcode OUTPUT
IF (@exitcode <>0) OR (@sqlerrorcode <> 0)
BEGIN
RAISERROR ('SQL Backup job failed with exitcode: %d SQL error code: %d', 16, 1, @exitcode, @sqlerrorcode)
END

This error has only happened one time on this box but we have seen a few other errors lately and are trying to determine if this is a software problem or a server/hardware/network problem.

Any help you can provide will be greatly appreciated.
Thanks
David Sharpe
Geographic Solutions