I have the exact same motherboard and the exact same issue.
Win7 x64 Pro
Biostar A880gz
AMD 8-core FX 8120
8gb DDR3 Gskill Ripjaw
HIS Radeon HD7970
Logitech G19
Logitech G13
Mionix Naos
Razer Megalodon
Netgear N300 (WNA3100)
USB randomly fails and all devices refuse to work. Beyond that, my boot locks up if I have my mouse plugged in--it has onboard memory, which the computer then tries to boot from. I can't even get past the boot logo splash--the speaker just makes an endless, shrill beep that makes me long for death.
I have to unplug my mouse anytime I reboot, but once I get to Windows, I can plug it back in and all things run fine. All my games and programs run amazing, but when the computer employs any method of power save mode (monitor off [as I shut off sleep/hibernate]) it's anyone's guess if the USB ports will remain active. I've shut off all power saving modes for the USB ports, flashed bios, tweaked bios, switched jumpers, had a priest bless it, and now I'm checking the internet.
It's good to know someone else is having this issue, as that can be an indicator if we have a reason to turn to the vendor and let them know there may be a series of bad boards. Though, admittedly, I dread the thought of replacing the MoBo off of a fresh build (even with Win7's Out-Of-Box Experience tool).
If there are others with this issue, I'm betting it's a set of poorly soldered boards. We might be out of luck and have to cry warranty to Biostar and see if they can't help us out.