The Microsoft knowledge base which is located here : MS KB Missing Optical Drive
This KB article has step-by-step instructions, for both Windows XP and Windows Vista, on how to delete upper and lower filters in the registry and even offers you a fix-it wizard (downloadable MSI) which you can download and it will fix it for you. The above requires you to reboot your computer once done.
If you are still having issues with any optical (CD, DVD, BluRay etc) type computer drive then you can try and install the latest motherboard drivers for your make and model of motherboard (sometimes this is also known as the chipset drivers). To obtain these you will need to go to your motherboard manufacturer's website.
To establish what motherboard you have you can use a few utilities; some of the more popular ones are SIW, Everest (I suggest Home Edition version 2.20 as it's free) and Belarc.
SIW can be obtained here
Everest Home edition can be obtained here
Belarc can be obtained here
Adaptec ASPI drivers can be downloaded and see if that helps. ASPI Drivers can be obtained here
on this link or here on this link
Also explained here on wikipedia
Also if you have any other burning software (multiple burning applications such as Deep Burner, CD Burner XP SE and Nero) installed as well as IN CD or Roxio then it is suggested you only have or stick with one burning appliction such as Nero as mutliple burning applications can cause issues.
Also as a last resort check the optical drive manufacturer's website for a firmware update for your optical drive. If they do then it is vital to read the Readme file to see what functionality it adds or what it does and also how to apply the firmware update. Follow those instructions to a T.
Ensure that you do not turn your computer off during the firmware update. If the power goes off while you are in the middle of the firmware update it will brick the optical drive, rendering it useless!!
If you are having issues with video playback then its always a good idea to try and use VLC
or Windows Media Player Classic
As for codecs if you are not sure what type of codecs you require to playback video files then get Gspot
Download it, use Winzip or the Windows XP unzipper to extract all of the files into a folder and run Gspot (a standalone exe) and then drag and drop the video file onto the Gspot window. It will show you what video codec the video uses and what audio codec it uses (if any for either) and also whether or not the video file is a valid file.
For Divx and Xvid you can install specific codecs for both Macs and Windows PCs from here, respectively:
For divx get the codec here
For xvid get the codec here
As a last resort for video you can try the codec pack which can be obtained from here
However, installing codec packs is not suggested nor recommended as it is likely to do more damage then good so you are better off installing the specific codecs that you require.
Please find below some free cd / dvd burning software :
Deep Burner http://www.deepburner.com/?r=download
CD Burner XP SE http://cdburnerxp.se/
A free useful utility for burning images and other things is ImgBurn (made by the same person who made DVD Decrypter) http://www.imgburn.com/
For any other free application needs go to http://www.thefreecountry.com/utilities/index.shtml
From the above link you can click on the relevant link(s) with regards to what kind of software you are after: CD burning, video playback, audio playback. The site will list all the free software in that category (you will have to scroll down some what but it is all there).
If none of the above helps with regards to iTunes it is always worth un installing and then re-installing a piece of software called Gears (ensuring you have quit itunes first): http://www.gearsoftware.com/wiki/index.php?title=DRIVERS:_Windows_-_Updating%2C_removing%2C_64_bit_versions%2C_etc
Tiny URL Of the above link is http://tinyurl.com/3cg946
Latest version of gears software for download here http://www.gearsoftware.com/support/drivers.php
PAQ for a question I helped with reference iTunes not burning:
If any of this is in the wrong order or is out of date if you could let me know.