Acer DVD drive's write speed decreased for mysterious reason!

[Base the Bass]

Hi.
I have an Acer Aspire 1414 with a Matshita UJ 831D dvd drive.Win XP home.

For a mysterious reason,I can no longer write dvd's faster than 2.4x
Also,when burning DVD's it is probable that in the last 30% of the process,it fails(depending on the brand of the DVD disc).I have used various brands of discs,at least 10.

I use Nero 7 and NTI DVD maker and they both yield the same results.

I called Acer and they said it was probably a conflict,and they told me to go to device manager and uninstall secondary ide/ata/atapi channel,and then reboot.The secondary ide/ata/atapi channel was reinstalled automatically,but that did not fix the problem.

the IDE advanced properties are as follows:

Device 0:
DMA if available
transfer type:ULTRA DMA type 2

Device 1:
DMA if available
transfer type:N/A

I also did the same thing for the DVD drive and it also did not fix the problem.

So my questions are:

* do you have any idea what's the fault and how I can fix it?

* could applications that install virtual drives,like alcohol and nero, have caused a conflict that slows my drive?if so,will uninstalling all these applications fix the problem?

* what is the proper way to bring the DVD drive configuration(I mean drivers etc)in the clean state it was when I first installed the system?

* will cleaning the DVD drive's lens help?how do I clean it?

* Has anyone noticed a similar problem with Matshita (acer) drives?


thanks for any answers!!!