Clicking on system tray icon does nothing

I did a new Windows 7 installation on an SSD over the weekend, and NIS 2012 appears to be working fine. When I click on the icon in the system tray for the first time after booting up, NIS appears on the screen. If I make any changes, or close it, it doesn't reappear when clicking on the icon. Right-clicking the icon displays a menu, and if I select an option e.g. check for update, it does that. However, the right-click menu disappears after having done that the first time.

 

This is with the latest build (19.6.2). If I install an earlier build e.g. 19.1, then everything is fine and works time after time. Of course, NIS updates itself to the latest build, and then I have the above mentioned problems.