Will read blank dvds but will not read prerecorded dvds or burn onto blank dvds. I have upgraded from Windows Vista to Windows 7, I keep getting a firmware error.

You will need to update the firmware of your DVD drive as told by the firmware error.

On a desktop system
To do this take down the model number and manufacturer of the DVD dvive (normally it is written on top of the drive itself so you may need to remove the screws that hold it in place and slide it out). Once you have the relevant information go to Google and type for example LG 24XDVD-DL-LS latest firmware update. Once you have found and downloaded the update just double click it to install.

On a laptop
Just type the model name of your laptop into Google followed by: latest DVD drive firmware update and then when you find it just download it and install.

NOTE: Be absolutely sure that the firmware update is for your drive as incorrect firmware can cause even more damage.

Download this program
http://www.freecodecs.net/fc/ImgBurn_2.5.5.0.zip

install it and run it
its a disc copying software but the reason i am saying to download it is that it will update your firmware for you

click write file to disc, then click on tools then move to drive then go to the last option on the new menu that says Check for Firmware Updates, click ok then click on the numbers listed below version( pick the one that is the latest) this will download the firmware file. extract the files from the downloaded zip and open the installer allow it to finish then click finish or exit. then restart your pc. Now try your dvd