Problems with my external hard drive

[Mushrooshi]

Alright:
So, one day, I decided to use iPartiton to partition my external hard drive. Ive done this a couple of times.

Now, when I reboot... It doesn't appear!

Now, here is the weird thing:

I plugged it in my sister's windows XP laptop, it works.

So I guessed it was a UNIX "Unclean Drive" Problem...

So I plugged it in to my mom's linux.

And it works perfectly.

So why isn't it working on my Macbook Intel C2D?