SL 2015 CU2 -- "Unable to open the message file ..."

We recently installed Dynamics SL 2015 CU2 on a server machine, and also installed a client on that machine. We then installed clients on two remote machines. The client on the server machine works fine. The clients on the two remote machines produce an error message box when starting the program. The message box says that the program cannot find the messages file. The message box is the following:

Any help would be appreciated.

Thanks,

Dan