"Cannot focus a disabled or invisible window"
That message should not be showing. A bug here.
Reinstalling vrtool will probably not help in cases like this
because the uninstall procedure does not delete vrtool current config
in the windows registry.
In the mean time, you may try to delete those
using Windows regedt32 program.
( Note!: Need Windows administrative rights for that)
1) Terminate vrtool.
2) Run regedt32
3) Delete HKEY_CURRENT_USER\Software\tecepe\Navigator\CurrentVersion\FormCartaNav
This will reset vrtool to factory settings.