Hard Drive not accessible, now not recognised by computer

I have my 1TB Maxtor External Hard Drive (purchased last year) and it worked perfectly fine until yesterday morning.

I left it plugged into my Computer (still working) when my computer updated itself (Windows Vista Home Basic). When I returned, the screen was black and it said 'Recovering files ...' and those files were on my external Hard Drive. After it finished 'Recovering Files' and updated the Windows, my computer couldn't detect the hard drive. First I thought, maybe because the hard drive was hot or something, and I unplugged it. In the evening, I tried to plug in and everything went okay except I couldn't access the drive. I tried defrag, used TuneUp Disk Doctor and even uninstall the recent updates. Nothing work. Still not accessible. But when I checked the HD with Disk Doctor, it detected all files in the hard drive. So, it probably still working.

I posted the problem earlier this morning and got a solution. But right now, when I plugged the HD back to my computer, the computer couldn't recognize it. It kept saying USB malfuction. I tried using different ports and my other computer, but still getting the same 'USB Malfuction' sort of thing.

Can anyone help? There are valuable data inside my HD and I really need them back for my work. Please help!