When in the Full Control mode, some special keys (such as Alt, Ctrl or Shift) are not working.
- Update your Viewer and Host to the most recent version. Follow the Updating Remote Utilities guide.
- Make sure the key is not "stuck" (keys stick after being rapidly pressed, it's a Windows accessibility feature). The easiest way to determine whether the key is stuck is to invoke the Windows On-Screen keyboard on the remote PC. The stuck key will be highlighted.
- Close and re-open the Full Control/View Only mode.
- Fully exit the Viewer (File ➝ Exit) and start the Viewer again.