Can't write to a CD with Vista Ultimate

I've upgraded to Vista Ultimate SP1, and am having trouble with my DVDRW CDR.
I'm using a Dell Insperion 9300 - profile was fine for upgrade. I did a
clean install using the full version of Vist Ultimate - reformating the HD
first. The drive will read fine, but will not write to a CD. I checked the
drivers, and all is up to date. I tried downloading and installing serveral
differnent burning packages, with no luck. I tried to uninstall it, and
reinstall it - but still no joy. I went to Windows support and suggested
deleting the upper and lower filters on the registry key - but when i went to
the key there were no upper or lower filters shown.

Any help would be appreciated. It's a Sonly DVD+-RW DW-D56A ATA.

Thanks,
John