Laptop Combo Drive Not Reading Properly

Greetings.

I’ll illustrate my problem briefly. I have a Toshiba Satellite A100 laptop bought new less than 6 months ago. Today, I was watching a Korean drama when I stopped it and inserted another Sony DVD-R into the matshita ujda770 (firmware 1.5) drive. Suddenly the drive refused to load the DVD even though it loaded 2 others perfectly just a few minutes ago. So I loaded a CD and it worked, I loaded another “real (not copy)” DVD and it worked. I loaded another"real" but it didn’t and I then reloaded my original DVD-R and it didn’t.

SO I’m confused, my drive is reading some types and not reading others… What is the problem?

Any solutions is appreciated.

Regards, Feng.