Windows 7: Verbatim 1TB External drive not recognised on boot

Hi I have windows 7 with a Verbatim 1TB external drive, the system is not recognising the external drive. When I switch it off and back on again it then recognises it and loads it in My Computer. I have another external USB drive which works just fine. This problem started after I formatted the PC and reinstalled windows 7. It worked fine before under the same OS. I tried another wire and plugged it into another port but still have the same problem. Anything else I can try?

Run a Disk Check if necessary using free Partition Wizard if Windows won't run it or doesn't see the drive.

You don't have Windows 7 on the external, right?

Disk check says everything ok, the drive works perfectly, but only after I switch it off and then back on when windows is already loaded. If it is on while windows starts up it doesnt get recognised.

I have a backup of c drive on my external but it's stored in a separate folder, so no I don't have win 7 on the external.

Have you updated/reinstalled the USB and SATA drivers?

When you reinstalled Windows, was the Verbatim External drive remain connected to the system?

I am just thinking whether that could be the cause of this problem. That comes from the general practice we adopt when installing Windows - not to have any other HDD connected to the system, save for the one on which Windows is installed.

Yes it was connected.

OK, now try this. It may or may not fix the problem but no harm will be done.

Download drivecleanup.zip v0.8.1 from Drive Tools for Windows . Unzip it and you will have two folders containing DriveCleanup.exe, one for 32bit and another for 64bit. Copy the one appropriate for your system into C > Windows > System32.

Unplug all external USB devices except your USB Keyboard/ mouse.

Open an elevated command prompt, type drivecleanup.exe and press enter.

This will clean up all old USB drivers and you will be starting with a clean slate.

Reboot your system.

Plug in your USB devices. Appropriate drivers will be installed for each USB device.

Safe remove all your USB devices.

Shut down your PC.

Plug in your Verbatim External drive, boot your PC and now check whether it comes on with Windows start.

If my reasoning is correct, this should fix the problem.

My reasoning: Windows was loading a wrong driver on startup. That came about because it was connected when Windows was installed and it continues to load the same wrong driver on startup. This procedure removes the wrong driver from its store and you have put in only the right drivers. ( I periodically flush the system with drivecleanup.exe and when I do, I reassign the correct drive letter to my external backup drive so that backups go to the right drive.)

Did that but still having the problem, hard disk sentinel is showing 83% health:

17 errors occured during data transfer. This may indicate problem of the device or with data/power cables. It is recommended to examine and replace the cables if possible.
At this point, warranty replacement of the disk is not yet possible, only if the health drops further.
It is recommended to examine the log of the disk regularly. All new problems found will be logged there.

It is recommended to continuously monitor the hard disk status.

Good work done there.( though I do not know how good Hard Disk Sentinel is.)

We never suspected a hardware problem since unplugging it and plugging it in resulted in a normal operation.

Try to get a replacement from the vendor instead of waiting for it to deteriorate further and living under a sword of Damocles.

Needless to say that you should backup all your data and not to rely on that drive further.