NBU 6.5在线备份MS EXCHANGE 2003报code 1 的错误

Question

定制了一个备份策略，每天自动备份，备份报了一下错误：

2008-12-6 19:55:06 - granted resource xxxnbu-hcart3-robot-tld-0
2008-12-6 19:55:06 - estimated 133976948 kbytes needed
2008-12-6 19:55:06 - started process bpbrm (9060)
2008-12-6 19:55:07 - connecting
2008-12-6 19:55:12 - Error bpbrm(pid=9060) from client xxxMAIL01: ERR - failure reading file: Microsoft Information Store:First Storage Groupxxxx Mailbox Store(xxxMail01) (BEDS 0xE000FE7C: )
2008-12-6 19:55:12 - Error bpbrm(pid=9060) from client xxxMAIL01: ERR - failure reading file: Microsoft Information Store:First Storage GroupMailbox Store (xxxMAIL01) (BEDS 0xE000FE7C: )
2008-12-6 19:55:12 - Error bpbrm(pid=9060) from client xxxMAIL01: ERR - failure reading file: Microsoft Information Store:First Storage GroupPublic Folder Store (xxxMAIL01) (BEDS 0xE000FE7C: )
2008-12-6 19:55:12 - Error bpbrm(pid=9060) from client xxxMAIL01: ERR - failure reading file: Microsoft Information Store:First Storage GroupLog files (BEDS 0xE000FE7C: )
2008-12-6 19:55:08 - connected; connect time: 00:00:01
2008-12-6 19:55:12 - mounting 8190L3
2008-12-6 19:56:04 - mounted; mount time: 00:00:52
2008-12-6 19:56:06 - positioning 8190L3 to file 7
2008-12-6 19:57:14 - positioned 8190L3; position time: 00:01:08
2008-12-6 19:57:14 - begin writing
2008-12-6 20:24:08 - end writing; write time: 00:26:54
the requested operation was partially successful(1)

The job was successfully completed, but some files may have been
busy or unaccessible. See the problems report or the client's logs for more details.

其它备份任务都正常，这个错误不知道怎么排查，诚心求教；