Look into a firewire interface (although sadly these look to be on the way out). I had a year of grief with a USB interface and haven't looked back since going to firewire 5 years ago. I also think Reaper may be part of the problem, have you tried any other DAW's? Cubase is the way to go....Reaper to me looks like how Cubase looked 15 years ago, and more buggy! Also, check your Windows power settings. Newer versions of windows seem to want to enforce power saving options on you, you always want this to be Max Performance mode. How many USB devices are you trying to use? If you try and use USB hard drives at the same time as a USB audio interface that would cause big issues. Other obvious things like trying another USB cable, different USB port etc? Good thread here on some diganostic tools to get audio running for reaper. This looks like to much work to me! http://forum.cockos.com/showthread.php?t=30896 Just out of interest, what is your latency set at? I always needed at least 12ms with USB!