A disk or read error is a sign of a hardware problem. The drive has bad sectors that the program can not read.
Consider creating a disk image of the problem drive first. Every attempt to access data can increase corruption, or can cause the damaged drive to fail entirely. After successfully creating an image, you can use the image file as an input for GetDataBack.
Creating an image is often preferable to simply plowing through. During the image creation, the program reads every sector exactly once, while the recovery process might read some areas several times. On the other hand, scanning the drive with a low sophistication level might leave broad areas untouched, thus actually reducing the stress compared to creating an image. This consideration especially applies if you are looking for only a couple of files. Please read a discussion on this topic.
In the end, this is your data and your call. You might also consider stopping the recovery attempt altogether and shipping the drive to a lab.
This message is displayed if the program encounters an error reading from a drive. This error is not recoverable, but you can ignore it.
You have the following choices:
GetDataBack reads data from the hard drive in blocks of 64 sectors (32 KB). If the read operation fails, and before the program reports the error, it can Retry the operation for each sector or skip the entire block. Auto lets the program pick the approach. It is almost always advisable to skip the block. Doing otherwise puts stress on the damaged drive with usually no benefits. You can choose the strategy in Tools->Settings->Data Recovery->Bad sectors.
See also: Create image, Image, Sophistication level