Quote Originally Posted by CantDecide View Post
Apparently the Mac doesn't have a active bad-block searching program, but I'll have my friend with a PC run a few tests.
Open Disk Utility, select the disk, choose erase, click security options, select "Zero Out Data", click OK, Erase. This will zero every sector of the disk, if there is a bad block, it will map it out. If you have a lot of time, select 7-Pass erase, this will pretty much guarantee that every sector of the disk is performing correctly.

Tech Tool Pro, Drive 10, Disk Drill, Drive Genius are all OSX options if you have data on the disk and want to do a non-destructive block test. Some paid disk utility programs have free trials that let you test a drive and then you only have to pay if you want to recover data.

Cheers!
ChinaV