I have tried to open the Nexetic Shield client, but it doesn't open. Only the Nexetic logo quickly flashes on the screen and then disappears.
1) Remove the installation of Nexetic Shield and make sure that folder %ProgramData%\NXShield is either empty or doesn't exist any more.
2) Then download the newest client version from the server and reinstall the program. Remember that you need to order a new password in activation phase to complete the reinstallation.
This usually helps to solve the situation.
A problem like this has sometimes happened when client has been switched off for some time, or when an older Nexetic client version has been removed from the user's computer before installing the latest version.