This message indicates that the given sector on the device could not be read. This problem could be caused by either bad media or a corrupt filesystem on the device.
To correct this problem try the following:
Check that the filesystem is in a consistent format with the fpck program. This program can check and repair DOS or HFS filesystems.
Take to media to a Mac or PC machine and rewrite the media and see if the problem persists.
Replace the media.
If the problem persists, contact your System Administrator or your service provider.
For information on how to configure or disable System Alerts, click here.