Cant Format my drive

My Passport says that I need to format the drive. I used it on another computer and it shows everything on that computer. It has Vista on it. I took my Passport to my other computer and it says no writable partition. I need to format it for this operating system. (Windows 7.)  So, I went to computer management to format the drive. However it says the drive is formatted and is a healthy partition. So why wont it read the drive so I can write to it?

does it have a drive letter?

I have the same problem.

Infact, it tells me that the drive may have been corrupted