i have a similiar issue. i have entered a ticket with support.
all i get now is the map navigator.
Do you get similar error as stated by Mark ? or you don't see the NTM application all together and just see the map navigator ?
If you just see the map navigator and not the NTM main window. Please check your OS task manager and try to find the NTM app there, right click the icon and maximize the menu item.
Let me know, if that helped.
I believe this issue was resolved, I did give you instructions to change a value in the config file.
Could you try the following
Please go to the Network Topology Mapper install folder and open
the file called “SolarWinds.NTM.Client.exe.config”. You can open it into notepad.
Path: C:/Program files/Solarwinds/Network Topology Mapper/
“NTMCredCleanup” app setting and set it to FALSE. Save the file and open NTM
Let me know if this procedure didn't resolve the issue.