DVD-RW drive not working right.

Have a Dell Studio MT Core 2 Quad/Windows 7 Professional that I got 5 months ago. First problem that came up was the the power supply mysteriously died a month ago and Dell had to send someone to my home to replace it. Now another mysterious problem has cropped up. When I insert a CD or DVD into the DVD-RW Drive, nothing happens. It was working fine until suddenly a couple of days ago it stopped working. If the disk is a movie DVD, nothing at all happens when I insert a disk (it is defaulted to play upon insert). But if I start PowerDVDx software after I insert (it came bundled with the computer), it will play the video. If I insert a CD (for example, if I am trying to insert new software from a CD), nothing at all happens. If if go into Windows Explorer and try to click or open the D: drive (which is the DVD-RW drive) it simultaneously ejects the disk and at the same time tells me to insert a disk. When I reinster, it tries a read for a few seconds, and then ejects again with the same message - no matter how many times I do it, the same result. The computer also comes bundled with Roxio Burn and it was engaging that program at the same time it was ejecting the CD. I disabled Roxio Burn with Task Manager so it no longer is triggered when I insert the disk, but the same result still obtains. So, is this drive yet another cheap piece of junk that needs replacing, just like the power supply, after only a few months or is there some other explanation/solution? Thanks.