versions

My cameras have been constantly losing signal and also just plain freezing for periods of up to 30s - 1min. I can actually see a live feed for only about 4 seconds before it freezes/loses signal again. I've tried different versions: 4.4.7.4 (x64), 4.4.8.4 (x64) and now 4.4.9 (x64), no luck...