SL2100 Error 64 will not go away

[It wire techs]

Hi

I have a client with an NEC sl2100 that has an error on extension 101 Error 64. It goes away when I plug in my laptop but as soon as I disconnect it comes back. There is no switch or internet connection in the phone room and it is analog COs with digital phones so I needs none. How do I get this error to go away. Ive tried to clear it but it just comes back

 

[jsaad]

If I recall correctly, adjust 90-10-64 to not set.