Regarding your inability to start 2.6.1524 on Win7 with old config file:
I have studied the opencpn
.ini file, and see no obvious problems. It starts up OK on my XP system, if I make the obvious local directory changes.
So, if you have the time, here is a debug method:
1. Rename you existing opencpn.ini to something safe, opencpnbackup.ini
2. Start opencpn 2.6.1524. It will use default values, and should come up.
3. If the default .ini runs OK, then we need to isolate the problem in the old config file.
4. Restore your old config file. Use an editor to remove sections/lines one by one, saving each time, and trying to run ocpn with the edited config file. Sooner or later you will discover what section/line is causing the startup problem.
You may safely remove some entire sections from the config file for testing, just to simplify the problem. All of the Plugin stuff can go away. [Settings/ObjectFilter] can go away. [Settings/AIS] similar. None of your navobj data should be affected.
Of course, I would remove these section one-by-one, since any one section may be the culprit we are looking for.
I'll help you through this if necessary.
This is relatively important, since many 2.5 users will experience the same thing on an upgrade to 2.7, and we need to nail this one.
Thanks, and good luck