I turn on my ext. HD, connect it to my MacBook Pro with a FireWire 800 cable and the ext. HD icon won't show up on my desktop. I tried different cables and it still won't show up. On the System Profiler application, my ext. HD is recognized as an unknown device when it's connected to a FW port. (SEE ATTACHMENT) Is there any way to make my computer recognize my ext. HD? Do I need to download any special software? (ie: firmware updates, drivers, etc.) I recently repaired my disk permissions.

Computer Specs

- MacBook Pro manufactured in 2006 with 15" screen
- 2.16 GHz Intel Core 2 Duo Processor
- Currently running on Snow Leopard (10.6.8)
- One FireWire 400 port and One FireWire 800 port
- Two USB 2.0 Ports

External Hard Drive Specs

- LaCie d2 Quadra Model
- 500 GB Hard Drive
- Supports eSATA, FireWire 800, FireWire 400 and USB 2.0

If you need more information, please let me know.
Please help me out. I need the solution.

How is that external setup, HFS+, NTFS or FAT? OS X uses HFS+ (Mac OS Extended)? OS X uses HFS+ and can only READ NTFS (unless you use third party shareware).

I have no idea how the ext. HD is set up as. The ext. HD used to work well without a problem back when my MacBook Pro was running on Tiger. Now that it runs on Snow Leopard (it never ran Leopard), I'm having problems with the ext. HD.

You know how to get to your Disk Utility...
Does your LaCie drive show up in Disk Utility?
If yes - try selecting the drive, and then click Repair Disk (different from Repair Disk Permissions)

I just used Disk Utility, turned on my ext. HD, connected it to my MB Pro by using a FW800 cable and the ext. HD didn't show up on DU.

What 3rd-party programs can I use to make my MB Pro recognize and/or repair my ext. HD?

If your System Profiler does not show that hard drive properly, and it does not appear in Disk Utility, then your external hard drive is likely bad - or the Firewire interface in the hard drive may be faulty.
Did you also try a USB cable?
If the hard drive also does not show up through USB, then that makes it more likely to be a failed hard drive...
Have you tried your LaCie on a different Mac?

I tried different cables (USB 2.0 and FW400) - didn't work.
I connected my ext. HD to a different (and old) Mac running on Tiger (10.4.11) - didn't show up.

Also, I have a new MB Pro running on Lion (not sure which version) and I didn't test my ext. HD on that MB Pro. (It probably won't work...)

I hope there's nothing wrong with the drive in my ext. HD. Its shortcut button is flashing just fine...

If your LaCie does not show up on two different Macs, then it's likely that the hard drive has failed.
It's possible that the power supply in the LaCie case has failed, so remove the hard drive from the LaCie case, and put the hard drive in a different enclosure to try out that possibility...

I don't think the PS has failed. Like I said, the shortcut button is working.

If I put the drive in a different enclosure, should I go with this kind?: http://www.lacie.com/us/products/product.htm?id=10330 (My current enclosure is not rugged like that.)

If the drive has failed, does that mean the data is gone? I'm worried...

What is a 'shortcut button'?
Do you mean the power light on the front of the drive?
That does not tell you anything about the condition of your data.
If your drive is not accessible in its enclosure, then you need to move that hard drive to another case.
If the case is bad, the drive may still be OK. If the drive is also not accessible when using a different case, then you data may be lost, or may be only retrievable through a data recovery service.

Here's an example of a good external, if you want something other than LaCie brand.
http://eshop.macsales.com/item/Newer%20Technology/FWU3ES2HDK/

Yes, the shortcut button is the blue light that's located in front of the ext. HD.

I'll try that enclosure once I get more money.

Try to Reset Your PRAM (http://support.apple.com/kb/HT1379) to see if that helps.

I tried that. Didn't work.

I tried that. Didn't work.

Does it matter if you turn the drive on first and then plug in.

I always plug in and then turn on the external drive. I use the reverse process when I shut down.
Eject ED, then turn off external drive, then unplug.

I have one external drive that will work on only one of my MacBook Pro ports and not the other.

I have 2 different ED and I think it is the LaCie that only works in one port.