Not too sure where to post this.
This problem occured when I wanted to copy a DVD video. I used DVD Region Killer and DVD Shrink. When I started the DVD Shrink programme without the DVD Region Killer, the programme crashed and since then I cannot read any DVD, even my HL2 CE disc, it states "Please insert a disc into drive D". Solved this problem once by formatting my computer. Sigh... Don't want to format my computer as the activation for HL2 is a long process. :a