i have Acer laptop ,  DVD  Does not work , only works in Safe Mode
my anti-virus is free avast and i disable all shield - same result -When you say it doesn't work, please explain EXACTLY what happens when you insert a cd or dvd. Also, does Explorer see the drive?Sorry for being late to respond. Because of the circumstances in my country 
When i insert a cd or dvd. it Begins to spin rapidly and do not SHOW icon . Then stop the drive spinning. It seems that there is no cd Again, does Explorer see the drive? And what happens if you insert a BOOTABLE disc and then reboot (make sure the cd drive is the first device in the bios boot order)? does Explorer see the drive?
no ....
what happens if you insert a BOOTABLE disc and then reboot
it work well ...( Example: When i insert a  Norton Ghost cd . and reboot  it works)

With thanks ..Forum And AllanHere are some things to TRY:

1. Uninstall the drive through Device Manager.
Restart computer. The drive will be automatically reinstalled.
or...

2. Delete Upper & Lower Filters
 http://support.microsoft.com/kb/982116
Restart computer.
or...

3. Download, and run Restore Missing CD Drive patch
Double click on cdgone.zip to unzip it.
Right click on cdgone.reg, click Merge.
Accept registry merge.
Restart computer.
or...

4. Go to Device Manager, click a "+" sign next to IDE ATA/ATAPI Controllers.
You'll see two items:
- ATA Channel0 (or Primary CHANNEL)
- ATA Channel1 (or Secondary Channel)
Right click on each of them, and click Uninstall. Confirm.
Restart Windows. They'll be automatically reinstalled.Before starting the previous procedures. For clarification: video or audio CD or DVD  work well
Problem only in  software and games DVD  Providing COMPLETE and ACCURATE information in your first post would be helpful.

So it's only one or two discs that don't work? In that case, try them on a different system and see if they work there. If they do, I'm not sure what to tell you except maybe your cd drive is on the way out.Actually I'm sorry
i try them ( many cd & dvd ) in different system : they work well