Sounds like your hard drive has a corrupted buffer partition used for pause/live playback. Your only options are formatting hard drive or just playing back recordings while you can access them. They can’t be played on another box. Could also be hard drive is starting to become faulty. Have you tried unplugging box & leaving it for a while? You might be lucky.
There are various Freesat pvrs about: Humax 1100s was more reliable, plus older Humax Foxsat HDR model but without apps. The newer Freesat pvr is made by Arris, but quite expensive. Hope this answers your questions.