Problems with external HD

Hi, i'm not that all knowledgeable about computers, but not that ignorant either.
I'm in france, and just got a brand new Toshiba with windows 7 home premium x64 on it. On the other hand, i got my old hard drive sent from home which my father devised (he's an engineer, and it was cheaper). It's IDE.
When i first connected it to the system it worked fine for about 2 hours (could 'see' it and could get files and do stuff), but after that, each time i try to use it, the system recognizes it for about 2 seconds (you can see the Disk with a letter on the My computer window), and then prompts this message that says "You need to format this disk to use it. Format or Cancel" I click format, and it says it can't format the disk because it's protected. I already got all of my important files out of it, so recovering is not my objective, i just want to get this thing functional again. It's not the letters, and after it says it cant format the disk, it stays ON, but it's nowhere to be seen on windows. Not in My computer, not on system management, drives, etc.
I need to format this to free some space up from the laptop's disk, so please, if anyone can help, i would greatly appreciate it
Thanks

Thank you, but none of those works for me. drive disappears from 'my computer' almost as soon as it appears, followed by the prompt to format it, so i can't check it. I don't want to buy a new one, i know there's a way to get this fixed!

More details of the external hard Disk drive may perhaps get others cracking on it.

Is it a branded one or did your father buy an external casing and put a HDD into it? Is it USB powered or powered externally? For how long had it been used (is it on its end of life?)

Could you try it on a friend's computer and check whether it behaves the same way?

As you have said it is a very old one, an IDE at that, and you have nothing important on it that you may want to recover, and you want to revive it only for data storage - which may prove to be risky. If it turns out to be a severe hardware problem and BER (beyond economical repairs) then we achieve nothing trying to make it operational.

Considering all these would you not be better served with a new spanking external HDD like the Seagate GoFlex Ultraportable external HDD? ( I do not work for Seagate - just my thoughts :) )

The Hard drive is just an IDE put into a case for data storage. It is powered via USB. I hope that helps, and if anything, i can open the case if there's anything important to identify on the disk itself.