Have you cleared the status in StableBit Scanner to see if the issue comes back?
To do so:
double click on the disk, click on the arrow next to "file system scan" and click on the button with the green circle on it, and select the "mark all damaged file systems as unchecked" option. This will clear the status and cause it to rescan the disk at the next opportunity.
Also, a surface scan may not detect file system errors.
The surface scan detects areas of the disk that are unreadable. Not that are corrupted. The file system scan uses chkdsk actually, to find corrected file system entries (and to fix them).
