Windows 7 loses my portable hard drive
I am using Windows 7 Professional edition with a Seagate USB External hard drive for my backups. When first connected with the USB cord, my computer immediately finds the hard drive and everything works great. After a couple of days or even more, the computer can't find the Hard Drive for my backups. When I click on My computer, it doesn't even show the drive. If I unplug the USB cord and replug it in, Windows finds the drive right away and we are ready to go again. For how many days, I don't know. Kind of frustrating when it decides to lose the drive and my backup is scheduled for that night. Any suggestions?
Note that the drive in question is not my main hard drive but a secondary hard drive.