I have a 2.5 120gb drive which I put in a octigen pata enclosure. the Pc sees the drive,It shows all the "it is safe to remove stuff" but I cannot access it in windows explorer to input or output files, it does not show up in the tree in my computer etc.
Right click on My Computer --> Manage --> Storage --> Disk Management and check to see if that drive shows up and is possibly conflicting with another drive.
I went to a computer shop, they said the drive needed formatting which I couldn't do because I couldn't see it or access it on my PC. He exactly as you said on a Vista PC in the store where the drive was visible formatted it and now its fine. He said some drives do not come formatted some do. Thanks for your help Dorango