does windows recognize the hard drive first of all? I'm guessing from what you've said it comes up as a removable device on my computer but won't let you access it? whilst connected have a look at what drive letter it is should be something like e: f: g: etc etc.

Open command prompt/MS-DOS and type chkdsk x: where the x is the corresponding drive letter of your hard drive so you are going to type for example chkdsk f: or chkdsk g:

It will then attempt to check the said drive for errors. See if it can do it and also what error message comes up on command prompt