xn902 licence issue ??

Hi i have 3 of these registers , just lost one a few weeks ago with backlight issue , now today one register on boot says "there is an error in your licence file" they are no dongles attached never needed them and both machines are networked together , i took out the flashdrive from the register with the backlight problem and put it in the one with the licence error and all seems fine for now , biggest problem is i had accounts setup networked between the two and all have gone and have no paper trail of the amounts, so i presume the register with the licence issue was the tracking master , so will details be still on the old fash drive which is now in the register with the backlight problem, help on either problems would be appreciated,
regards kent.