irpwns :
Do you have another computer you could hook up your external hard drive to? You can always try a system restore on your computer. Or you could even try to uninstall and reinstall your external hard drive software on your computer? Maybe it needs to be updated?
Just a few ideas off the top of my head. Hope it helps.
I also could not access my HP ext HD (all our pics, music and videos are located), tried the internet, and no results until I thought of something that helped me... My Netgear router (I paid about $70 CDN) has a USB connection that I can connect ext hard drives. Just because windows cannot\won't read, the router will, through the network ... I am currently copying all the important files from the HP Ext HD back into my desktop and laptop... Hope it works for you, Good Luck.. Frank