Because of an external hard drive crash, I've developed a theory that Spotlight under 10.5.8 has been trashing this particular Maxtor (yeah...I know...Maxtor drives are garbage historically) drive somehow. After testing my theory over the last 2 weeks (reformatting, reloading the files, and testing the drive on my other Macs with 10.4.11 and 10.5.7), CONSISTENTLY on the 2nd day of testing the drive with my 10.5.8, the drive gets trashed and cannot be recovered with **, TechToolPro, or even DiskWarrior. Under 10.4.11 and 10.5.7 on the other Macs, the drive appears to perform normally and reliably.
Today I'm reformatting the drive again, but this time I'm making the drive "private" so that 10.5.8 Spotlight won't touch it. In a couple of days, I'll let Spotlight see the drive again and see what happens. I'll get back with the details within a week, but I'm putting my money on Spotlight 10.5.8 being the problem.