DVD burner not reading,playing and burning dvd disc

My dvd burner is not reading/playing/burning dvd. I used to do that though.However,after burning 2 slides for more than 5 hours, the problem started. Here are the things that ive done so far.
1.clean the lens and mirror of the burner using cotton buds and a little of alocohol.
2.checked the cable setting for master/slave.
3.checked the jumper setting
4.ensure that DMA is running under device manage>advance settings and then reboot.
5.Upgrade firmware,however nero sites says no firmware update for my burner.maybe its still updated, i just bough it Oct. of 2008.
6.Change the cable settings for master and slave,before master was dvd burner and slave was cd rom. Now master is cd rom and slave is dvd burner.
7.downloaded drivers and install
8.Downloaded dvd decoders and install
9.checked the BIOS for DMA enable
10.Tried the Regedit thingy and then reboot.
11.Tried the uninstall/install dvd drive(asus)/ IDE primary,secondary in advance settings(device manager) and then reboot.
12.Install/uninstall nero 8.
13.not yet tried other burning software though.but ill consider that one.

Nothing works permanently. There are times that it will play,read videos and data. However, when I remove the dvd disc, the problem will return.

Good thing is its reading,playing and burning cd’s. I dont think that I have to buy a new one , coz thats the suggestion of others in the forum,however its sometimes playing,reading dvd data and moive.

What else should I do ?



Need more info.
Computer stuff, etc.