Only offering a solution to update the firmware, not to solve your msconfig issue.
To update the firmware on my DVD drive I needed to close all my startup programs and used msconfig to do so. Hoever when I used the disable button it failed to do work and subsequently I get a Access Denied error whenever I try to run mscofig. I am the sole user and the administrator for the machine. I have tried creating another different administrator account but this hasn`t solved the problem. Any ideas on how I can get msconfig working again please ?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic