I'm on great terms with the legion in my game and I've been collecting dogtags for them from the NCR troops so things have been even better. Now when I go to Cottonwood Cove they are all hostile. Before you ask, no I don't have any faction armor on, and also there are no companions of any kind following me. What gives, anybody else having a problem with the legion randomly going hostile? All patches are up to date as well.

Did you recently wear any faction armour? It may be bugged, in which case you need to re equip that faction's armour, then unequip it (not sure if it shows the disguised reputation in your pip boy).

Other than that, not a clue I'm afraid...

I had a similar problem with Vera's Outift from Dead Money, it still acted as Faction Armour, pressumabely because it uses the White Glove Society Tux model if your a man. Reset all Reputation, when I took it off, all Legion shot me on sight. Do you have Dead Money?

Its weird, I waited 3 days and went back and they were no longer hostile. I'm not sure what happened because I hadn't done anything to anger them, hadn't worn any faction armor, and didn't have any companions with me when I went there. Seems like sometimes factions randomly turn hostile. Oh well looks like they reset and everything is cool now.