For some reason the computers can’t access the cfg file. You can see what the path should be by going to working computer and going to help - about and look at installation path. All computers must use same path.
once you set the path on a computer it should remember unless the path is not accessible. 

If it is not asking you search for it, but to reinstall, it's either looking at the wrong file or you have something else odd going on.

Did you maybe install a trial version of the newer Timeslips? Or did you update some machines and not all?

Try doing a right-click, Run As Administrator and see if that doesn't resolve it.

If not, browse to the LOCAL INSTALL (abbreviated LOCLINST) folder on the server and run setup.exe to re-install.