Yes....I have certainly noticed....although for me it is most prevalent during regular programming, and mostly in the evening. Sure is great trying to watch something like "Two And A Half Men", and having to write your own script as you go along, to fill in the dialogue that is dropping out every 20-30 seconds for 2-3 seconds at a time!!
And yes, it is only on this channel....Fox HD West.
When sound and video problems occur on a single station you can pretty much guarantee the problem is the source station not the distributor (in this case, Bell)