Mixed Up Channels

I just started looking at this forum so Im not sure if this issue has been addressed. Just recently my channels will intermittantly switch to another and then back and forth. This seems to mostly be in the evening and not weather related. I have a standard D10 reciever and all my transponder signals are in the high 80's and mid 90's except for 4,12, and 20 which are at 0 being normal for me. When I have the channel problem, those 3 start showing signals in the high 70's and a couple of the others drop to 0. Any ideas? Is it my LNB or Reciever going bad?