After 3 full days of intensive search on the Web, I came across this forum.
Problem: "me too" with a twist.
System: Compaq A900 running Vista Home Premium. Automatic Windows update. Tons of apps. Latest was PowerISO to burn some learning videos.
Symptoms: In the midst of burning some DVDs and some CDs using PoweISO, DVD drive did not recognize anymore CDs (DVDs work just fine).
1. Tried all CD/DVD in another computer running XP SP3. They all worked. Not a media issue. Not a PoweISO issue.
2. Installed Nero 7 in both Vista and XP machines. Continued burning successfully DVDs and CD in XP machines. Vista only recognized DVD media but NOT CD.
3. Went through all update drivers, registry manipulation with Up/Low limits entries. NOTHING helped.
Diagnosis: XP works fine, Vista is the culprit.
Work-around solution: Suspecting Vista and all its updates are the issue, Compaq A900 was formatted and restored back to its factory condition. Installed Power ISO. DVD drive now recognizes CDs again.
My take: DVD drive (hardware) is rarely a problem. "It's the software, stupid!" It took 4 full productive days of my life to work-around this problem.
I am sure it will come back some day, next time it's just 1 day to restore the computer to factory state then re-install everything else.
Bill and his billions are looking prettier and smiling every time I wasted my precious day to fix his problem (or more precise, his built-in traps to make sure users like us scattering like bugs looking to get our tools fixed so we can be productive and contributing to his billions).
PS: some were asking "Why not restore using Restore Points?" Well, somehow Vista resets/deletes/ignores/forgets its functionality. I manually created at least 3 points, all were not kept by Vista. For this particular incident, Vista did not offer any Restore Point for me to go back to. It's another issue all together.
But all points to Vista and its BIG BIG problems! So use Windows at your own risk, be prepared to scratch and reload, pay your shrink so you still have your sanity.