Hi,
I also was blocked when I tried to log on to the Navdata application. The log on page would simply freeze despite receiving a message through my Firefox browser that I was already logged in to Navigraph!
The solution:
1 - Go into Firefox settings, then select the “General” icon in the upper left-hand corner.
2 - Scroll down the page to the “Files and Applications” section. In the Applications box, you should see “Navigraph-desktop” in the “Content Type” column.
3 - The corresponding Action should be “Use Navigraph Navdata Center (default)”
In my case, it indicated “Use Firefox” and this is what caused the error. Once I made this small correction, the Navdata Center worked perfectly.
I hope this helps.
Charles