[TIH-11] Restore ends with "failed to read sector"

From a bootable CD with TIH 11.0.0.8053, I performed a restore. Originally, the image was created of a partition that had been prepared with chkdsk /r. After its creation, it was verified as flawless. Now, at the very end of the restore process, I received "Failed to read sector xyz on Harddisk 4". Retry did not work, Ignore-all however did.

Does this mean that some sectors in the image are not ok, or some sectors on the target partition?

How come that ignoring some sectors did not spoil a successful restoration?