MCI Error (MMSystem 263)

I am trying to sort out the above problem on a computer when playing a multimedia CDROM.The full fault is:-
MMSystem 263 This is not a registered MCI device.
One clue might be that I had to recover a backup version of the Win.ini file about a month ago,I have compared details with a win.ini on another computer and it seems the same.
I have replaced files Msvideo.dll,Mciavi.drv and Dciman.dll.
I have reinstalled the Microsoft MCI Motion Video Device(Media Control) but no joy.
The machine isold still running Windows 95 but the owner does not want to upgrade.
The Microsoft knowledge base gives a list of MCI faults but nothing on 263.

Steve