I have an LG HL-DT-ST 4521B Combo Drive that reads DVDs and burns CDs. I had not used the drive for quite a while. Then, I tried to burn a CD, but when I click burn in nero, it asks me to insert a CD, even though one is already there. However, it reads all my DVDs. It does not read even new scratch less CDs no matter they are blank or full. Is there a solution to my problem?