[ubuntu] External Hard Drive unable to read after Ubuntu install

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http://ubuntuforums.org – Hello, I am a new ubuntu user. I installed ubuntu OS dual boot with windows 7 for school and my external hard drive which I have connected all the time stops working. When I open My computer in windows 7, I see the local disk that corresponds to my external drive (name changed from MyBook to local disk:F). When I try to open the local disk, My Computer just freezes up and nothing happens. When I try to access the external HD from ubuntu, it said something about not being able to mount. Please help! There are alot of files on my external that I need to access. I have no idea what happened. (Hardware)