What version of the client are you on? If the system is a laptop, does this happen on the laptop keyboard as well as the external keyboard? Does the keyboard allow you to enter the username? Does the mouse work? Does the keyboard work pre-EEPC (i.e. in the BIOS)?
Do you have the correct language file set installed and selected?
If you do, you can try to refresh the language file set, by
1. In machine props > Files, uncheck the file set (eg EEPC51 LANG: German (PreBoot, German/Swiss Keyboard) ) 2. Sync machine to delete file set 3. Back in machine props, check the file set again. 4. Sync again to install the file set again.