On System Center Data Protection Manager (DPM) 2010 with March 2011 hotfix I got the following error when backing up to tape:

ID 30101 Details: The request could not be performed because of an I/O device error (0x8007045D)

This is an error that was originally fixed in DPM 2007 with a hotfix http://support.microsoft.com/kb/970868 , but reappeared on my 2010 install.  It can occur with large tape backups that span more than one tape.  I fixed the error by adding the following registry key, a reboot wasn’t necessary:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft Data Protection Manager\Agent]
"BufferQueueSize"=dword:00000001

[UPDATE]

I’ve had the same problem with DPM 2012 SP1 and the registry still fix worked.