I don't know if I'm posting this in the right place, but here goes...
I've been using a firewire external hard drive with my mac and recently it's been doing strange things like locking up and not letting me unmount it or use the files on it at all. I haven't lost anything on it, and at one point I even tried cleaning the whole drive and starting all over... I guess what I'm wondering is... could it be some kind of setting or something I've got on my computer or do you think the hard drive is just going?
Lock-up issues generally occur on PC computers due to Delayed-Write Cache processes, which I assume apply to Mac computers as well -- since this directly involves read-write buffering to your hard drive. (By the way, I am not a professional computer tech person, but merely a learn-by-trial/error PC user)
I personally experienced such lock-ups most recently with an old 80GB Western Digital Firewire drive as well as with an old Maxtor USB 2.0 200GB drive, both drives having 8MB internal cache.
Despite many reformats, double-checking that all cabling was secure etc., in addition to disabling the Delayed-Write Cache feature within Windows XP for each drive, I nonetheless encountered no improvement in the performance of either drive, as each drive still continued to lock up, especially when downloading large files via the Internet as equally as much as while transferring large files from drive-to-drive.
Given all of the "research" that I did (essentially filtering through online forums etc.), the only conclusion drawn was that such lock-up issues are usually specific to manufacturing, so it appears.
Since purchasing two new external HDs: (i) a Western Digital "MyBook Essential" 500GB USB 2.0 drive (16MB cache) ($129 plus tax from CompUSA); and (ii) more recently, a LaCie 500MB USB 2.0 drive (8MB cache) ($119 plus tax, also from CompUSA), I no longer have any such lock-up problems -- and each drive presently has Delayed-Write Cache "enabled" (by default in Windows XP).
Since I am not a Mac user, this info may be of no consequence to you in helping you to solve your lock-up issues. But suffice it to say, both drives began to lock-up only after roughly two years of usage -- both drives performed without incident up until that time -- so perhaps the lock-ups simply began due to aged internal mechanical parts.
I always recommend to everyone that they back-up their data to other removable media, i.e., DVD disc etc. for safekeeping.