Registry Checker Error

While starting one Win98 PC, an error message comes in Windows Registry Checker Popup “Windows encouuntered an error accessing the system registy.
Whindows will restart and repair the system registry for you.” there is only one option “OK”, if I click on “OK” it restarts and comes up with the same message, I can work on the PC with the message on screen, but how can I solve the problem.

Thanks in advance.