I expect the sysconfig file has en-KE in the logonCultureName field and Epicor does not like that. What culture do you want?
Try editing the sysconfig file with the configEditor (Run ConfigEditor.exe in the Epicor client folder)
This is what ours looks like.
If that is the issue then I expect you will need to check the sysconfig file on the server. The client will take a copy from the server so if the server copy has an issue all the clients will have the issue.
Thanks @bmanners. Cannot save one i edit the config editor