LG dvd 4166b will read and burn, but not play dvds

Hey guys, i purchased an LG dvd - rom in Feb. and never tried to play dvds untill now, altho i have burned dvds w/ it. Heres the problem, it will read any dvd insert but, it will not play them...ive tried: store bought, burned dvd movies, a burned back up for my quake4 and a burn back up of all my cds i made into a dvd-mp3 disk. It also will not let me "drag and drop" anything from the drive onto the desktop or folder. when i try to drag and drop, i get : "can not copy'ect': The request could not be preformed because of an I/O device error."

also, if i D-click the drive it says: "Drive"G" is not a valid Win32 application"

i am COMPLETELY lost here because the drive will read disks and burn but, not play.

also, i can "explore" what ever dvd i insert and all the info is there...so, i know it's reading them correctly.