No programs installed - Add/Remove Prog

All programs have disappeared from the Add/Remove Programs screen in Control Panel. The window is blank with the message "No programs are installed on this computer". This happened with no apparent cause. I assume it's due to a corruption in the registry or an index file, but not sure where to look to see if can repair. obviously can't repair from the add/remove window, as no windows components show as installed either.
Any suggestions?