MY 1TB passport studio works on mac but not pc

Hi and good dat to all,

i purchased the above hard drive about 2 weeks ago, plugged it into my macbook pro with mountain lion OS, and it worked like a charm. I installed all the necessary software it came with on the drive.

Now, i want to transfer music from my PC to the harddrive, but when i plug it in via USB, all that comes up is the WD UNLOCKER. When i unlock, nothing else comes up.

Please help !!!

Thanks in advance…

The drive is formatted for Mac and will not work on Windows unless you reformat or use this application Catacombae - HFSExplorer