It probably is your dvd player. Try playing it in your pc and see how it goes. Your discs sound like Riteks but here is how to tell if you got real Riteks. Download
this tool. Insert one of your Riteks into your dvd burner. Then scroll to the option 0E- Pre-Recorded Information in Lead-in. Then click the read dvd-rom structure button. If you have real Riteks then the second line should end with this: RITEKG..03. If you get an error trying to run this program, try installing ASPI32 layer 4.60
here then try the prog again.