There is some outstanding advice in this thread.
 
I'm glad your system is working well now.  Just for the historical value, it should be mentioned that switching from WDM to ASIO is not always going to be a solution.  Devices have drivers, and some of those drivers are well-written, others not so much.  With any device, you have to either try both WDM and ASIO, follow a manufacturer's recommendation, or go with the advice of the DAW support staff.  For example, my Tascam FW-1884 has always run better using the WDM driver, and this is fairly well-known advice for that particular unit.