Hitachi HF-W6500 Instruction Manual page 148

This equipment may record the following events in the event log while the OS is running
Table 4-2 Error / Warning Eventlog (While Windows® 7 running) (2/2)
Disk
CR-ROM
atapi
・Source:Disk, Event ID:11 event may be recorded in the event log when a USB device is
connected or disconnected or when the system starts for the first time after a storage device
is added, even though the USB device or the storage device works without any problems.
Those events are recorded due to the specifications of the OS and do not affect the
operation of the system.
For detail, see the following web site.
Microsoft technical information
Disk event ID11 may be recorded when you connect USB flash memories or USB disks to
the computer which installed Windows 7 or Windows Server 2008 R2.
https://support.microsoft.com/ja-jp/kb/2537729
・Source:CD-ROM, Event ID:51 event may be recorded in the event log. As long as you can
access the DVD drive, there is no problem.
・Source
Event ID: 11 event may be recorded even if errors occurred in reading from
:atapi,
the drive and the error recovery was successful after reading normally from the other
drive. (D model only)
If the error is recovered, an error log occurs once. If it happens multiple times
consecutively within 1 to 2 minutes, there is a possibility that the error recovery has failed.
Source
Document number：2537729
4-3
4. PRECAUTIONS WHILE THE OS IS RUNNING
Event ID
11 Error
51 Error
11 Error
Type