Me and my friend have the same motherboard (and almost the same set up as me except he got a different PSU, RAM brand, and GPU) and I've never had this problem but the other night we were trying to play some R6Vegas co-op but couldn't because of this so it became my problem. For some odd reason he is unable to have his keyboard and mouse plugged in at the same time as his ethernet (onboard). If he has his ethernet plugged in he can only have either his mouse (Razer Diamondback) or keyboard (Saitek Gaming keyboard) plugged in, but not at the same time. If he has them both plugged in at the same time his mouse just flashes randomly like a hdd activity indicator would. But when I unplugged the ethernet (on a whim) it stopped blinking, stayed solid, and they both worked. I went into the BIOS and tinkered with some I/O and controller settings but it didnt work. Every time I plug the ethernet back in while the mouse is plugged in Windows just says that it cannot recognize USB device. But when the ethernet isnt plugged it I see it listed in the device manager just fine. I'm really lost and have no clue what the problem is. I thought maybe an IRQ conflict or something. These problems all started the other day when he unplugged his keyboard and plugged in my USB flash drive to put the new Bleach on it. Apparently it's been doin this off and on ever since. Any clues?