what exactly happens when you place a dvd in the drive?
does it just fail to read the disc?
try holding down shift and close the drawer,keep shift held down for 10-15 secs and see if it spins up then open powerdvd and try to play it.
my dvd drive is very choosy and sometimes i have to do this with rental discs or well played dvds,may help.
also try uninstalling the drive via device manager and restart the computer,windows will find it again and automatically reinstall it.sometimes this helps if the drivers have got messed up in some way.