I upgraded by Vista Home to Vista Ultimate and now my DVD player isn't working. I don't even see when I open my computer icon. I get the following issue
Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)

See Microsoft Knowledgebase Article ID: 314060:
Your CD drive or DVD drive is missing or is not recognized by Windows or other programs (http://support.microsoft.com/kb/314060)
"Your CD drive or DVD drive is missing or not recognized by Windows or other programs, so you cannot play or access a CD or DVD. This issue might have occurred after you installed, uninstalled, or updated a program or Windows Vista."