The product will watch the SMART counters of your drives continuously with a process called dhcore and warns you if something suspect happens (Bad block replacement, temperature too high, CRC errors,...) On my computer it tells me that the Ultra ATA CRC Error count was changing too quickly. Some of my files seems to be corrupted. I've change the ATA cable of place within the computer (he was bent) and I have no more CRC errors. If you only need to read the SMART counters, HD Tune is free ! Regards.