Ivan,
When you install a new plane there will often be new files for that plane installed in some other locations apart from the 'aircraft' folder (as a general rule, some don't but the more complex/interesting the plane the more likely it adds other folders

). The most common are:-
the gauges folder (where the gauges for the instrument panel live),
the effects folder (to see things like smoke when your wheels touch down),
the sound folder (often little sounds for the panel like the click noise some switches make or GPWS whooping noises)
the modules folder (where FSSound.dll and other .dll's live)
There are some utilities that scan your installation of Flightsim and remove surplus gauges etc (as long as no other plane uses them too) - you could try one of these to see if there's something extra got into your FS9 that doesn't need to be there... Search for 'GaugeExplorer' or 'FlightSim Manager' under FS2004 Utilities on Avsim - I haven't included direct links so you can have a look at the descriptions and see if they suit what you want before deciding to download...
From your original post you mentioned a 'Lago' folder - this (as far as I know) won't be anything to do with our fleet... Do you have any planes or addon scenery by Lago? Is there a 'Lago' folder in your FS9 installation?
And finally (and forgive me if you do this already) have you run a virus check on your system and checked your hard drive for errors and defragmented? Problems in Flightsim can be caused by other issues in your computer setup because FS9 is such a demanding application...
I hope you can solve this Ivan, if you need any more explanation of my post please feel free to ask.