Dear developers and advanced users, I Am recommending You two tools, which are freeware and are perfectly accessible with screen readers. The best free tool for harddrive diagnostic, even for USB harddrives diagnostic is CrystalDiskInfo There is stable and also Beta release for this tool. Program is MSAA fully compatible and all controls can be reached by using standard Windows keyboard shortcuts. Download this excellent tool from here. http://hiyohiyo.s181.coreserver.jp/CrystalDiskInfo5_1_0Alpha1.zip This is Alpha release, stable release can be downloaded from http://hiyohiyo.s181.coreserver.jp/CrystalDiskInfo5_0_4-en.exe For finding remapped sectors, which are not set as remapped but are corrupted, it is best to useSpeedFan application. Install it and use smart tab and use extended test. The power of this tool is, that it is enforcing The harddrive test, similar algorithm, which is being used by harddrive manufacturers to assign bad sectors as remapped. You can compare The number of remapped harddisk sectors may be, that after executing short or extended test from SpeedFan, The number of remapped sectors can increase. Do not be engry to this program, it is not writing bad sectors, it is only recalling special harddisk internal test, which can find bad sectors and will reassign them as remapped. This can save You alot of data. Unfortunately, this program is not supporting so much USB external harddisks. Download SpeedFan from here. http://www.almico.com/installspeedfan446.exe And I Am recommending You to use Marking program available on The WEB site of The Crystal disk info program. The WEB site address is here. http://crystalmark.info/?lang=en