[XenonSurf]

There may be issues with corrupt savegames if you overwrite saves, use autosaves or save in 'heavy' action, that may cause to crash the game soon after you load it, meaning the save got corrupt. Try out if it's fixed now when saving correctly as described, else I have no idea what may cause your crash.

Your install is correct from what you tell. Real Navigation shouldn't matter, but: in this case you must set appropriate Game Options when in the bunker, but this is done by default, so if you didn't change anything it should be on Realistic settings and not clashing with anything. When in the bunker, go in the Options and check if all is ticked except the external camera which you can leave unticked if you want to use it.