I always play as a law abiding citizen. I don't wear any gang or Legion clothes. I restart from a last save if I ever get negative karma.

I've done nothing against the NCR, yet every time a Ranger sees me they turn hostile, no matter what I'm wearing. I haven't killed any NCR nor done any quests against NCR. I've also never pick-pocketed, murdered, or done anything that got me negative karma. My reputation with NCR is neutral.

Why am I being attacked?

Also, some NCR mercenaries tracked me down and threatened that I should increase my reputation with them in three days. I did the solar quest and rescued the captives in boulder. I've tried doing other quests but NCR and rangers attack me when I get close.

How do I get NCR and Rangers to stop attacking me?

are you wearing anything related to the Brotherhood of Steel? there is bad blood between these two factions as well...... i know for sure that BoS armor causes the NCR to attack.

something peculiar that happened to me, was the NCR randomly attacking me whenever i walked around with E-DE as a companion. i would always make him wait when i was going into any NCR location, even with me being idolized by the NCR. game is pretty buggy anyways so it could be just that. sorry my friend, a lot of us are experiencing frustrating things. you're not alone....

I wasn't aware the game had BoS items. I'm not wearing any. I've learned to save every 3-4 four minutes because Boone can blow the head off a hostile NCR or Ranger at any moment. What really svcks is that I won't be able to do any NCR or Ranger related quests. I hope that doesn't effect the main story...