What does code B5 (or could be 85) mean?

I have a panasonic DVD recorder DMR-EZ45V. It recorded ok from tv for a while. Then I got a error code B5 or 85 on the unit. I was recording a program which appeared to be recording but when I played it back it just recorded static, as if the tv was not tuned in. Have not got a clue what is going on. It formats some dvd's but not others even though they are of the same make. Any suggestions of what is going on.