External (USB 2.0) hard drive shuts down USB port and is not recognized until port is disabled and then re-enabled

2) Run this command from an elevated command prompt (right click on command prompt shortcut, select "run as administrator"):
Logman start USBForumTrace -p Microsoft-Windows-USB-USBPORT -o USBForumTrace.etl -ets -nb 128 640 -bs 128

3) Run this command from an elevated command prompt:
Logman update USBForumTrace -p Microsoft-Windows-USB-USBHUB -ets -nb 128 640 -bs 128

4) Execute your repro scenario (in your case, plug both of the cables into the PC before plugging the other end into the drive).
 
5) After you have a repro of the problem, run this command from an elevated command prompt: 
Logman stop USBForumTrace -ets

6) Search on the machine for “USBForumTrace.etl”

7) Post that file and c:\windows\inf\setupapi.dev.log on a public folder on http://skydrive.live.com and post the link here.

Thanks,
Mark

I too have a similar problem that is fixed when I uncheck the  "Allow the computer to turn off this device to save power" box but the box is rechecked upon reboot every time. Is there a way to make this stay permanent. I have an ASUS A8N-SLI nith nforce 4.

I'm not sure whether my problem is the same as the one here but let me try it.

I had a bear of a time getting a new WD My Book Essentials XHD 1.5 TB installed (spent quite a bit of time on the WD chat board), but Windows 7 finally said it was installed.

During this process, Windows 7 downloaded and installed a slew of updates while I sat and waited. Then I rebooted as instructed and went back to trying to use my new XHD. 

Now, when I try to hook up my new XHD and another XHD, it doesn't show up as a Hard Disk Drive when I open Computer off of the Start Menu. The WD Smartware shows up as CD Drive (J) but no XHD. When I plug in other XHDs, they show right up.

I did what Mark [MSFT]suggested above - that is uncheck the "Allow the computer to turn off this device to save power" check box.  Reboot the machine. 

I had this happen with another XHD that I returned, thinking it was the XHD. I am frustrated and clueless as to what to do. 

Any words of wisdom would be most gratefully appreciated.

I've had problems similar to Djembe (the first poster) with several external hard drives. I plug one in, it turns on, then dismounts and starts clicking. Except when it dismounts it shows a dialog box saying I need to format the drive. Sometimes the drive stays on for several minutes, sometimes less and sometimes doesn't turn on at all. I've never had a drive stay on longer than 5 minutes. Externally powered drives (3.5in desktop drives) work fine.

This problem developed immediately when I installed Windows 7 Home Premium (the final version). Under the beta build 7100 and Vista, all these drives worked fine. I tried the fixes described in this post but none have worked.

I'm using a Dell XPS M1530 laptop which has the Intel motherboard chipset PM965. Intel and Dell only have drivers for Vista and have said they may or may not update drivers. Are there any plans to update these drivers on Microsoft's side? With only a 200GB internal drive, not being able to use an external makes this computer unusable. In the worst case I'll have to reinstall Vista.

 Externally powered drives (3.5in desktop drives) work fine.

 Are there any plans to update these drivers on Microsoft's side? With only a 200GB internal drive, not being able to use an external makes this computer unusable. In the worst case I'll have to reinstall Vista.

The usual problem with USB powered drives is that the computer USB ports don't put out enough power to run them. Either the ports themselves are below spec (500mW) or the external drives are above them. Or you're sharing the available power with another USB device, however low powered it may be. If the drives came with a supplementary power connector that would be a clue.

MS doesn't write the chipset drivers but if Intel or Dell decide to provide new ones, or legacy drivers for the chipset MS might distribute them (as they do for others already) through Windows Update.

Although Mark's solution to this issue works during that computing session (in other words, as long as I don't shut down the system or go into sleep mode or hibernate), it requires re-doing it whenever I restart the computer if I want to use the external, which basically makes it no more useful than my previous fix of disabling and then re-enabling the USB ports.  Is there a way to either make the change permanent or set up a particular setting for whenever I plug in the external drive? 

Although Mark's solution to this issue works during that computing session (in other words, as long as I don't shut down the system or go into sleep mode or hibernate), it requires re-doing it whenever I restart the computer if I want to use the external, which basically makes it no more useful than my previous fix of disabling and then re-enabling the USB ports.  Is there a way to either make the change permanent or set up a particular setting for whenever I plug in the external drive? 

Along the lines of slim hope, do you have other USB devices plugged in? Do you have any unused USB ports? Sometimes the ports are inexplicably linked in pairs (esp. front and rear ports) and a device plugged into one can affect devices plugged into the other. I was recently dealing with that situation with a USB WiFi adapter in one port and a flash drive in the other. The WiFi adapter/USB port would behave much the same as your external drive if the USB flash drive was present during boot. Without the flash drive present the WiFi adapter initialized just fine.

You could try one of those external USB2 hubs that has power doubling (similar secondary USB connection as your drive uses) in case that makes a difference. The drive should only require one USB cable itself with that setup.