Problem with playing movie DVDs on my laptop

[MGMT]

Hello everyone, I hope you can help me with this problem.

Whenever I insert a movie DVD in my DVD drive, nothing happens and I can't play the DVD. If I try to open the DVD drive in explorer, it asks me to insert a DVD.
I don't have problems reading/burning other DVDs.

What could the problem be?

My computer is an Acer Aspire 5920G with Vista
The DVD drive is a hl-dt-st dvdram gsa-t20n ata

[makshaw17]

Follow these steps...

1.   Click the Start button, click Run.
2.   In the Open box, type Regedit, and then click OK.
3.   Click the plus sign (+) next to HKEY_LOCAL_MACHINE.
 
 NOTE:   When you click the plus sign (+) next to a folder, it will expand displaying the folders it contains in the left-hand pane of the Registry Editor. When a folder is highlighted, its contents will be displayed in the right-hand pane of the Registry Editor.
3.   Click the plus sign (+) next to SYSTEM.
4.   Click the plus sign (+) next to CurrentControlSet.
5.   Click the plus sign (+) next to Control.
6.   Click the plus sign (+) next to Class.
7.   Click {4D36E965-E325-11CE-BFC1-08002BE10318}.
8.   On the right hand side of the window, click UpperFilters.
9.   Click Edit on the menu bar.
10.   Click Delete, and then click OK.
11.   On the right-hand side of the window, click LowerFilters.
12.   Click Edit on the menu bar.
13.   Click Delete, and then click OK.
14.   Click File, and then click Exit.
15.   Restart the computer normally.

Also clear the startup by start->msconfig->click on start up tab-> disable all and enable only the security program-. apply and restart the computer.

Let me know wats next.