User Authorisations do not work When Applied

Dear Experts,

I have a situation here that is quite baffling. I go into user authorizations, set full authorizations on the sales module for a user. Then click update, the system does not update automatically and I have to click the update button twice. Once I close the authorizations window and open it again the authorizations previously set have gone back to what they were before. This is happening for all users.

Does anyone know what could be causing this ?