11/11/09 - Here is the Hotfix.....
Just posted on the microsoft website.  http://support.microsoft.com/kb/976972

We have confirmed it works, and posters from this site http://social.technet.microsoft.com/Forums/en-US/w7itprohardware/thread/38f25c1d-de67-4c74-8845-2cd3a15d8e41  have more to say about it.

 

* Received 10/22 From Microsoft Engineering.
Bob, sorry about the delayed response. We have confirmed the issue in the NVidia chipset with 64bit EHCI buffer handling on systems with greater than 4 Gb RAM. We have prepared a code fix to disable 64bit addressing on the problematic NVidia chipsets and preliminary results look good. We are now conducting exhaustive testing in our labs to ensure there are no regressions with this fix and that he problem is fully corrected. When ready it will be released through our normal channels.

Thank you again for contributing to our understanding of this issue.

11/3/09 Note: We get email daily from around the world from people having various problems with USB connections including other Chipsets than those shown below. The only common link is Win 7 64 bit OS. Thank you for your emails, but we have no other information as yet except MS is definitely working on it. As soon as we hear anything it will be posted here.

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Windows 7 64 bit only.
USB external hard drives or other USB devices  lose their connection and stop working on systems using nVidia nForce 6 and up chipsets.

Note: We are receiving 2-7 emails everyday from around the world about this problem and Windows 7 has not even been released. The big question is will this be resolved before thousands of people have it? 

11/2/09 This isn't correct and should be changed. I have an Nvidia nforce 520 chipset and suffer the same problem and others with the same chipset series have the same issue. It should read 5 and up.

* Received 10/16/09 With reference to the below fix.
Hello,
For all systems with 4 gb ram there is a better temporary workaround, I think:
disable in BIOS the option Memory Hole Remapping. After then the system uses only 3 gb and the problems with the usb connection is gone. (The system uses only the memory, which can be addressed witch 32-Bit.
I tried it with an Acer Aspire X1700.
After the problem will be solved, it's easy to enable the bios option again. 3 GB is not much, but with all office applications there are no performance problems. Gaming may be a problem.
Best Regards R.H.

*New 10/5/09 - Received this email and "It worked for us"
Until this problem is resolved (if it ever is) it seems we only have these choices.
1) Live with the USB problems with 64 bit Windows 7 which is unacceptable for us.
2) Use this fix that will disable about half of your installed memory but solve the USB problem.
3) Revert back to 32 bit Windows 7 or stay with your old OS.

Please contact us only if you have more information about this problem. We get several emails a day asking for help.  Win7Tips@Gmail.com

This was proposed on http://social.technet.microsoft.com/Forums/en-US/w7itprohardware/thread/3aae3b66-6a1a-47e8-ad1b-b20b68eaecf8?

------- Snipped suggestion from forum ---
For those of you hitting issues with a hang or a failure to transfer data, you can try the following...

From an elevated command prompt (right click on the command prompt shortcut, run as administrator):
1) Type "bcdedit /set truncatememory 0x80000000" (no quotes)
2) Reboot
3) Go to control panel -> System and Security -> view amount of RAM and processor speed.
- It should report 4GB (2GB available)

To undo this, open an elevated command prompt again:
1) Type "bcdedit /deletevalue truncatememory" (no quotes)
2) Reboot
3) Go to control panel -> System and Security -> view amount of RAM and processor speed.
- It should report 4GB

BE SURE TO UNDO "deletevalue" THIS FIX AFTER THIS ISSUE IS RESOLVED so you get all your memory back.

Another way to do this and it saves more or your memory.
Saw this on the TechNet forum:

I have a little improvement for the temporary workaround that will allow us to use all the RAM minus 1 GB. In my case this is 7GB instead of the 2GB proposed by the original workaround.

Calculate your amount of memory in bytes in hexadecimal and substract 1 . You can use google to do the calculations or use scientific calculator. If you have 8GB like me just type in google (without quotes) "8 * 1024^3 - 1 in hexadecimal" and the result will be 0x1FFFFFFFF . For 6GB it is 0x17FFFFFFF and for 4GB it is 0xFFFFFFFF .
Type "bcdedit /set truncatememory 0x1FFFFFFFF " (no quotes) in an elevated command prompt if you have 8GB, or use the other hexadecimal numbers for other amounts of RAM.
Reboot
You will have, depending on the number used in step 2, either 7GB or 5GB or 3GB available, but the problem is solved.
I have not tested it with higher amounts of RAM, but as I say with 8GB of installed memory and 7GB of available memory it works.
Thank you Mark for finding out the original solution.

It seems to be a slightly better option since you only loose a little bit of memory (1 GB loss vs 2 GB fixed max)

* New 10/1/09 - Nvidia release an updated driver.
http://www.nvidia.com/object/nforce_vista_win7_64bit_15.49.html
* We installed it but it Did Not resolve our problem....

* 9/20/09 - Here is a fix we received. win7support.ciengi.com "It is a temporary fix till Microsoft releases a new USB port driver package. Also, this issue seems to only be on the nVidia nForce 6 and up chipsets."

* On 9/17/09 we received a email from MS Win 7 engineering requesting more information. They are now looking into this problem.

*Update - We installed Windows 7 Ultimate 64 bit RTM on our HP dv9700 laptop and it does not have any problems copying large files to a external USB drive but it does not use NVidia.
Some people believe it may be caused by the NVidia Chipset drivers.

Note: This does not happen when we use "Vista 64 bit" OS on the same computer.

Any brand of External USB drives crash 64 bit Windows 7 OS when transferring large files to USB from internal drive. After it crashes, "Unknown device" shows up in device manager. USB won't work and usually the computer locks up.

We tried both versions of Windows 7 Ultimate including the RTM.
We currently have it installed on 1 HP Pavilion Desktop, and one HP laptop. Both 64 bit OS, As of now only the Desktop is having this problem and it use's NVidia.
People report it does not occur with 32 bit Windows 7 OS.

Problem:
Any brand of USB external hard drive (and other USB devices at times) lose its connection and stops working only when copying large files from internal drive to external USB drives.
The USB device may appear to work fine when Windows first starts up but later stops working (locks up computer) after large files start to copy. You must restart Windows to get the USB working again.
This occurs only when copying files large files TO the USB, not to the internal drive.

As per suggestions, we have:
1) Updated the BIOS from manufacturers websites.
2) Disabled power management on the USB hub for drives
3) Make sure that the BIOS setting for Legacy USB is set to on. We don't have this option in BIOS settings.
4) This is not a motherboard problem as it happens on three different MB we use.
Also tried three different USB drives and different cables.
We also reverted back to Vista 64 bit and Vista 64 does not have this problem
Please let us know if you hear of a fix.   Win7Tips@Gmail.com

A Microsoft Tech. support person did send us an email saying they could not duplicate this problem at their end. He said they have done extensive testing with many systems and have not had USB disconnect problems.
I find this hard to believe after reading a hundred or more people complaining about this on help sites. Our specific problem is with USB external hard drives but many people are reporting various USB device problems such as keyboard, mice and more.