I have a Lacie external 250GB HDD(formatted for Mac) that stopped getting power. I took it apart and removed the HDD that was in there (Seagate Barracuda 250GB) and connected it to one of my PCs so I can boot into Knoppix to get the data off.

When the drive is connected to the slave IDE of a PC, and I power on the computer, it powers on for half a second then shuts off. I have now tried this on 3 different computers and they all get the same result...power on for half a second then power off. Once the drive is removed, all the PCs start up fine.

Any idea what could be the culprit here? Thanks!

It sounds like the drive is physically broken. Are you sure you are setting the jumpers correctly? Jumpers for both drives MUST be using the same method in order to work. If the existing drive on the IDE cable is set to master then you need to set the 250 to slave. Conversely, if the existing drive is currently using CS (cable select) then you need to use CS on the 250. When using CS the drive on the END of the cable becomes the Master. Some WDigital drives may have a special setting for master alone. This can't be used in conjuction with slave. Lastly you need to be using an 80 wire IDE cable. The 80 are color coded. Usually blue on the MBoard end and then grey and then black on the other end.

Ok well heres an update:

I tried booting up the computer with just the drive set to master, and I get the same result. Power for less then half a second, then off.

I take it the drive is physically broken?

If you have data you need to recover you could try the freezer trick. Seal the drive in a non-static plastic bag and place in the freezer. When you take it out, connect and attempt runnning as quickly as possible. If it does run, don't shut down without recovering all your files. Plan ahead to have a target to copy to and plan which files are the most important. The freezer shrinks the parts which may allow the drive to spin up. A slight tap on the side of the drive may aid spinup too.