This doesn't have anything to do with the antivirus, the program or the scenery. The issue is caused by an error in your scenery.cfg, which was already there and it's surely a result of having edited it by hand. The installer tries to handle the most common editing errors, but some might slip through.
If you search your scenery.cfg file for 2291 string ( the error says ´2291 is not a valid value` ), you should see something that looks like an error.