Outlook 2000 'The operation failed'

I still run Outlook 2000 on Windows 2000 because it works and I haven't needed to upgrade yet.

Outlook now displays a message 'The operation failed' when started and then when the message is acknowledged Outlook closes again.

I have tried re-installing. I have tried uninstalling, then deleting all references to Outlook in the Registry, then rebooting, then installing. I have tried repairing the pst file. I have tried renaming the pst file and have Outlook re-create a new one. But there is no difference, I still get the same message.

Does anyone have any suggestions? My next course of action is to back up my files to CDs then do a complete new installation from the OS up.

Thanks

John