FF/Rewind dvr causing black screen that you cant get beyond

I have xfinity service  and a Roku express. I used the dvr function a lot but over the past 2 months it hasn't been working. I'll be watching a show, rewind it or fast forward it and then when I click play to watch the show again the picture goes black. I'm unable to fast forward past the issue either - the screen gets stuck in black and the only option is to exit out of the recording. Once this problem occurs with the black screen, that dvr recording will never play beyond the point where the screen originally went black.