Thanks for replying drpino!
UPDATE: I completely removed the Plextor and discovered it wasn’t set to Master. I decided to run the self-test anyway and it took approximately 30-40 minutes. Strangely it seems the blank DVD that I inserted for the test was burned (with what I have no idea but I guess it was part of the test). When the test was done, the tray ejected and there was no flashing lights indicating there was no problem with the Plextor. I set it to Master and connected everything, now the Plextor is burning at 4x again.
-D j K i l l a-