Picture and Sound Disappear for Between 3 seconds and 5 minutes

Got Verizon Fios 1.5 months ago. A week ago started having interruptions in picture/sound from Motorola HMDVR (HDMI connected). Happens frequently and then not for hours. Screen goes dark/no sound and returns after a few seconds. Sometimes screen goes to snow and snow lasts up to five minutes. Doesn't happen with DVD. Switched TV HDMI inputs (DVR and DVD), problem moved. Was there recently an upgrade to HMDVR that could be causing the problem? Never had this problem w/cablevision. Also don't seem to have problem with other HD STB's.