It may be that your drive has the incorrect driver, perhaps windows is picking it up as a non-writing dvd drive. It reads dvds fine? and just wont burn them - but did before you upgraded?
You can try re-installing the driver:
Start type "Device Manager" -> Enter
Find your dvd drive in the list of devices
Right click and select "uninstall" and press ok.
Then Click on "Action" (on the menu bar) and select "Scan for hardware changes"
Windows should re-install the driver and say successful. Give that a go, if not look on dells website.