could not lock file

I have a backend dbase that I used to be able to link with the front
end over an IP Address that hosting the back end.

Just revently when i try to link this i get an error message stating "
could not lock file" and it won't let me link the back end.
I don't want the backend data to be read only and i've never had this
problem in the past.

Does anyone know what is going on and how to correct this?

tks
Steve