I've occasionally been getting "S.M.A.R.T. Status Bad: Backup Drive and Replace" error messages for a 100GB Western Digital drive since I re-connected it last night after unsuccessfully troubleshooting a WIndows installation.

I fear the magnetic end of a dual-ended screwdriver may have accidentally got too close to the drive (I'd been using it error-free for weeks). No errors are reported when scanning the surface of the drive with Windows Disk Management, CHKDSK or the Western Digital diagnostic utility but the error would reappear, often at the next reboot (only to then disappear again after a few more reboots).

I checked the S.M.A.R.T. Disk information and nothing seems too alarming, except for the UltraDMA CRC Error Rate: the current value is 200, the threshold is 0 and the worst value is 253. How can the worst value be higher then the current value?! Would this indicate a problem with S.M.A.R.T. Disk Information that could be triggering a false error message? Thanks to all.

It is a long standing myth that bringing something slightly magnetic near a HDD can corrupt it or cause problems.

While this is true for floppy drives, hard drives are not susceptible to it. You'd need an extremely powerful magnet to damage data on a hard drive. A magnet near a hard drive WHILE it is on can cause problems with data currently being transferred, but that is it. AFter all, remember, there is a powerful magnetic inside the drive itself for the motor and actuator.

If you are getting "random" smart errors, I'd suggest backing up the drive and RMA'ing it, provided it is only that drive.

The 'UltraDMA CRC Error Rate' detected by S.M.A.R.T. does mean that your drive is defective, but depending on the cause, it doesn't necessarily mean that drive failure is imminent. If the drive electronics are starting to produce errors, then failure could happen soon. It could also be caused by poor contact at a solder joint, or between the drive electronics PCB and the drive housing. Either way, you should back up your data and RMA your drive.

Yeah change the cable first, see if that makes the errors go away.