External HDD disconnects/reconnects

I have a Western Digital Elements 1 TB USB 2.0 External HDD. It doesn't matter what USB 2.0 header I connect it to, back or front of PC, an error message will eventually pop up in my tray/task bar telling me the device can perform faster, and the HDD disconnects/reconnects. Some times this will happen more than once. How can I stop this from happening?

My external HDD:
Amazon.com: WD Elements 1 TB USB 2.0 Desktop External Hard Drive WDBAAU0010HBK-NESN: Electronics

Error message:

Thanks! All drivers are up to date. I disabled the speed message in device manager, we'll see if this fixes the issue.

This DID NOT fix the issue... the HDD randomly disconnected on me again, but without any USB error message in the try showing up.

I also disabled "Turn off this device to save power if necessary" options in device manager for USB. Made no difference.

HELP!!!

I have one answer to the problem I had external hard drive disconnecting. Microsoft Security Essentials found a Trojan on my laptop "trojandropper.win32/sirefef.gen!E" My external hard dive was connected to my PC and I never had a problem. I connected it to my laptop and it was fine for a while then it kept disconnecting. Two things started to happen. A pop up would ask to scan my computer I would click on it and it would not scan the external hard drive it would just close up. Then a pop up would show folders, I could click on and it would go to that folder and disconnect. I changed the USB cord, the place where I plugged the electric cord, I put the USB cord in a different USB slot in my computer but nothing worked. So now since the Trojan was found and removed the hard drive has not disconnected from my HP since the Trojan was removed a few hours ago.

Sorry--this worked for a while but the external harddive is back to disconnecting on an off.