My Book Home Edition looses connection with Vista

I have had the WD3200 external drive for a little over 2 years now with no problems and last week it suddenly lost connection with the PC.  I am using the E-sata connection to a Dell PC, running Vista.  Unplugging the power cord to the drive, and re-plugging gets it back on line, but it will drop off after some time period.  this has been going on since I first noticed the condition.  I have a backup program that runs in the middle of the night which is useless now.  any help would be appreciated

Have you tried updating your drives firmware?

You may be experiencing infrequent power glitches which is exactly what is happening to me.