Precision 4800 USB ports create high CPU

Despite having the latest drivers, a high levels of system interrupts occur on my Precision 4800 after a few minutes of USB connectivity, enough so that it occupies 16%+ CPU, or full time on a couple of cores. Haven't found a fix except hibernation, but it just occurs again a few minutes after waking up. It doesn't occur if I do not have a USB device attached. Machine can run for weeks without this problem until a USB device is plugged in. Posted this a couple of weeks ago, got a private message from dell asking for service tag info, which I supplied, was promised a reply the next workday, but instead dell went silent and my post was taken down. Hence this post. Anyone familiar with this problem?