Just bought this to dub vhs-c tapes to dvd+r disks, but after dubbing my first videotape successfully, I stopped dubbing, took out the first tape and put in another one, hit play and the machine dubbed about 15 seconds of it and then completely shut itself off. Tried dubbing 2 different tapes to another disk and the same thing happened again. Every time, I re-start the dubbing of the 2nd tape, it does about 10 - 15 seconds and stops. Any ideas on what is happening here?