Well recently went to Primm and repaired Ed-E, started the compaion dialog, when finished I went to the Vicky and Vance casino and Ed-E started picking fights with anyone in range. After I activated him and got the chat window, I set the companion mode on, opened inventory and unloaded a lot of junk items to reduce my weight, then while in tactics window set him to aggressive mode. Once I exited that window I brought up the other companion window (the circular one) and reset him to Passive. However once I entered the V&V casino, he started picking fights. Tried reloading the game and making sure he was in passive, but he just kept shooting. Thankfully after they were done with him noone attacked me, but once Ed-E was back up he went for Primm Slimm and was gunned down again.

You placed a food/drink item in ED-E's inventory. ED-E is classed as a creature and not a NPC. Hungry NPC sees this food/drink and concludes the only way to get it is to kill ED-E....or die trying.

I'm http://www.newvegasnexus.com/downloads/file.php?id=37796#fileanchor. Ed-e is loaded with food and from Novac to running around Vegas he has not been attacked by NPC's.

Happens to me all the time at Vicky and Vance's so I just park him outside. One of the hundreds of annoying game bugs.

Strange as this will sound it's not a bug. Everything involved is working exactly how it should be. It's just several factors (all working as intended on their own) are coming together to form a undesirable situation. Oblivion had almost exactly the same quirk with an archer near Bruma. The NPC wanted to collect arrows and if your horse had an arrow(s) in it's inventory (thanks to some bandit) it would try to kill your horse to get at the arrow(s).

Yes, the next patch is reported to make the required changes so sand-boxing NPCs won't consider your non-humanoid follows valid targets in their search for food/drink.

Now if they also prevent your idle humanoid followers from cleaning out your fridges at the Lucky 38 I would be happy. That's another case where the Sand-boxing NPCs, that are working correctly, are driving me nuts.

Is that what does it?

I thought it was because they all had guns out when I was talking to them (pre-Sheriff) and Ed-E was interpreting their interaction as an attack because of that. First two times it happened was just after I played Caravan with Johnson Nash.

There's a http://www.newvegasnexus.com/downloads/file.php?id=36623for that.

Are you sure it's food related?
I'll have to check that out.
I get this occasionally with EDE but have never been able to pin down what exactly in his inventory sets people off.
I know it's inventory related because as soon as I empty his inventory the problem stops.

This has happened to me too. ED-E got destroyed by the 1st Recon at Camp Mccarran, and as his dead body lay broken on the ground they cruelly leaned over him and made as if they were looting him! Nothing was missing thankfully, or I woulda had to show dem 1st Recon my wrath! :gun:
And yes, i had food on him, most of which i had just stolen from Camp Mccarran.

It also happened to poor Rex, too, inside Hoover Dam. Rex totally killed Quartermaster Bardon. :huh: