Problems when installing via dvd-drive...

Ok first off, im not sure if this is the right forum, wasn't too sure whether it should be under this or CD-ROM/DVD-ROM, but anyway im sure it's close enough to not matter

Right; ever since i reformatted my PC, i've been having serious problems when i try to install something from disk, i don't know about writing to disk since i only ever use my dvd drive to install things from.
There are a few problems but the main thing is that it takes FOREVER to install anything, for example: at the minute im installing Empire:total war, it's been installing for about 1hour 40mins and according to the installer still has about 50mins to go.

The other problem is that , when im installing something from disk it seems as though my computer is under a LOT of stress, which is obviously not right as I have a fairly powerful computer; the computer seems to 'lag' and it's virtually impossible to do anything other than surf the net (slowly), sound stutters a little, as if my computer really has to push to get it out and it sounds pretty bad and it's really just all the symptoms of, for example having lots of demanding applications running at the same time (which I don't).

The really strange thing is: when i check in task manager my computer doesn't appear to be under much stress at all - memory usage is around 500meg and CPU usage is low, like 20%.

I've tried pretty much everything I can think of;

- I tried using both older and newer firmwares for my drive
- I tried a different drive to see if it was the drive itself or just windows: turns out the drive is fine as I got the same effects when using the other drive.
- I've checked the connections to make sure nothing has come out a little or is damaged (I can't check another slot as my mobo only has one IDE slot)

My computer specs are:
CPU: Q6600 GO
RAM: 2gb Corsair XMS2
GPU:8800gt
My drive is a Lite-On LH-18A1H.

I should probably say that the drive doesn't seem to be spinning very fast, or at least it used to make a lot of noise when it was installing something and now it makes just a quiet hum.

Anyone have a clue as to what this could be?

you might have a dirty lense. try using a lense cleaner disc to clean the lense.

if that doesn't solve the problem you might want to look into a new optical drive.

Yeah I reinstalled the chipset drivers, and the IDE port seems to be running in UDMA 5 so there doesn't seem to be anything wrong there...