I got it two days ago, and it just wouldn't boot while Steelseries Xai mouse is connected. Before the bios screen, while those numbers appear at the lower right corner of the screen, it would just hang at "B4" and do nothing. As soon as I disconnect the device it continues booting. It's a real hassle disconnecting and connecting it after boot. I also flashed bios to 1.7 hoping it would fix it, but no improvement at all.
as i said i'm keeping the mouse as it is, with this kind of "fix"...not happy about it, but it's the only way i can get this mouse to work, and not "destroying" usb ports on the motherboard.....