I was having the exact same problem of intermittent white noise kinda sound after I updated to the recent drivers for UX2 v4.2.7.7. When I downgrade to the driver v4.2.7.6 the problem seems to go away. I opened a support ticket regarding this but didn't got a satisfactory reply from line6. I've been using UX2 from the year 2003 without any problems with win7. Now I have upgraded to win10 and was fine till the previous driver version. (Dont update to the latest driver version. Keep at v4.2.7.6)