Check the sample rate of your interface, and windows and your project. Windows sound settings if your interface is also being used as your audio device can impact the system if its bit rate is different than the interface and project. This happened once to me when I had windows set at 16bit 44.1 but my UAD interface was 24bit 44.1
When I started a new project it defaulted to 24bit at 48 and I got static until I went through and updated the windows sound setting to match my interface setting and project to each have the same resolution.
