LG RC6821W DVD/VCR combo player

Question

DVD-R discs that I have previously recorded on with this player, but not yet finalized, will not be read by the player later on. I'm even having trouble with the player not reading some commercial DVDs.

Also when I try to record on a new DVD-R disc, it will record from TV for about 10 minutes and then just stop recording.

Can you please help me with a possible solution?

Thank you
Richard.