drive not responding after hours of inactivity

I have a wd my book home edition 500gb external drive connected to my hp pavilion dv7-1245dx laptop via a eSata cable. After some time my drive "disappears" from my computer. It also cannot by seen under device manager although it is still physically connected and powered up of course. If I click scan for hardware it will eventually find it. Sometimes also after drive spin down and I try to access a file on the drive, it spins up but screen just freezes until I shut down drive. I have already reinstalled OS, reinstalled drivers, and even got a new drive. Can someone please help me with this. It does work fine with USB cable.

It might be, that in your BIOS your eSATA is not set to AHCI, and therefore when the HD is going to sleep, it looses the contact to Windows, as when in legacy IDE mode it cannot be detected automatic.
Either don't let the drive goto sleep, or (if possible) change the eSATA port to AHCI.

Unfortunately wd says the drive will always spin down after 10 mins. I also do not see anything in my bios that is specifically about the eSata port. This port is also a USB port, some kind of HP combo port that I had never seen before...yes usb cable and eSATA plug into it. Another trouble shooting step I used is loading UBUNTU live from a cd and the drive functioned perfectly even after spin down and being reaccessed.

Yes, Linux don't have the problem, but it also don't support some of the fast features from eSATA as Windows does (Linux works like an old DOS in this set AFAIK).

If you can't set it to AHCI, then I don't know what to do, if you can't stop it go to sleep.