I have to ask a simple and unlikely to be the issue question... What is your BIOS set at for the USB connections?

I've noticed several people bringing this issue up since mid Dec. but found little or no mention of it before then, all I can think of is a driver update around that time has a conflict, do you have a restore point around Dec. 1st, or can you try rolling back the sound driver, or network driver, or anyother driver that had a resent windows update. This is the only thing I can think off that would make it show up sudden, but at diferent times for difrent people, as it wouldn't rear it's ugly head untill the update occured. I also read one post where a person added a monitor with a usb hub built in, and he got the same symptoms, but they went away when he disconected it, if it's a combanation of hardware and driver, that woul;d explain why it is not affecting everyone.

I noticed that time range too, but I do have case documentation with EVGA dating back to mid-November. 
On one of my re-installs, I ran Win 7 fresh off of the install disk, without any updates.  This error happened within 24 hours of even that.
I also tried only installing Win 7, direct from manufacturer drivers (not letting windows update doing it), and this was also not a solution.
I appreciate your advice.  Hopefully we will get to the bottom of this as it seems  to be a pretty widely occurring problem.

It does not lock up, it's a matter of all USB ports ceasing to respond.
I still have full use of my PS2 keyboard, and it will boot, reboot, etc etc just fine.  Really, anything that can be done with keyboard only can still be done.

There are many people, including myself that have experienced this same situation.  You can read about them in this forum thread:

http://forums.evga.com/tm.aspx?m=120174

I documented my situation as completely as I could on the first page of that thread - and my symptoms match yours exactly.  My computer started doing it shortly after I put it together in early September, and I was running Vista 64-bit at the time. 

I took my computer apart on January 19th and shipped off my motherboard (RMA) the very next day.  The replacement motherboard would never get to Windows boot before turning off the power supply, so that board was RAM'ed as well. UPS tracking the 3rd board shows that it will be here this Thursday. I really hope tha you guys are incorrect that this is a software issue... if it is then I am doomed to have this same problem when the new motherboard arrives.

btw, mine was the same with my original 4870 GPU...

No its not os specific...well unless you want to lump them under windows...lol

I just had this happen to me while playing a game a few minutes ago.  It doesn't happen very often - I have only had it happen twice since I got my new system set up about a week ago.  Unplugging the mouse and plugging it back in let it resume functioning properly.

HalloweenWeed
I was using these:

Logitech MX-518 (gaming mouse)
Saitek Eclipse lighted USB keyboard

I'm kind of surprised I haven't run into these issues, it must have been a certain batch of boards or something.  And in case it helps, I had mine hooked up to a Saitek lighted USB keyboard at one point and have had no problems.  Other USB device is a Logitech G9x.

Edit: Yes, SATA goes through southbridge.

nighthawkf22

Hey stupid question you guys, you did update to the latest BIOS right?  I didn't see any mention of that in the thread...

I'm on S61J.

'course I did. I was running SZ2D.

didn't the real tech sound drivers hit around the time this started, someone try a driver roll back ? see if the problem goes away. I would but I didn't allow the update, so I'm still on the old driver, and I'm not haveing the issue.

I do not have this problem, but I did read about it on Technet.
If you have an nVidia Chipset there is a Hotfix from MS -> http://www.microsoft.com/...ED9&displaylang=en

"You may encounter problems when you move data over USB from a Windows 7-based or Windows Server 2008 R2-based computer that has an NVIDIA USB EHCI chipset and at least 4GB of RAM"
 I hope this is helpful:)

I'm not convinced that this is a software issue or a bios issue.  It's started happening to me again and I'm kind of leaning towards pwm temp.  Also what frequency do you guys run your pwm at?  I'm going to convert my system to water just as soon as I can get long enough screws to mount my scythe kaze 38mm fans to my feser xchanger 360 rad so I'll have water blocks on the mb.  If its a temp thing then it should stop once a water block replaces the passive heatsink on the mosfets.  If it continues then I will lean towards it being a hardware problem.

I'm leaning towards just getting a new board.  (anything other than EVGA).  Thus far, I've come to the conclusion that this board (my second one)...in addition to the other two identical boards I used for two other computers for a friend is nothing but trouble albeit possibly due to it not playing nice with other components/software or its a hardware/firmware issue.  Even the two EVGA GPU cards for the other two x58 board computers I built have their problems regarding fan adjusting below 60% which is not being addressed.

I'm surprized to have voice such negativity on the board and yet to have a EVGA employee/rep chime in to address issues.  When you look at newegg's feedback...they seem to chime in rather quickly to show they are concerned about the issue(s) a recent purchaser had.  The only thing that I've heard on the phone with tech is it must be another component that is causing the issues.

I still say my 1991 ABIT KR7A raid heavily overclocked raid configuration is MUCH more stable this my "new" builds using EVGA components.  Granted, the new one is faster and can play games much better...but that doesn't mean a thing if you can't complete a damn game or work with something when you have to restart the computer or deal with a mouse freezing up!  Hell, I'm still typing and using my KR7A configuration right now!

Nope, tried that already.  Mouse is not the problem.  I've got a few hardwired mice that do the same thing.  Microsoft intellimouse (even reinstalled windows without logitech's software...which led to the same results)...as well as a G5 and they both do the same thing.