The last time I ran a game of D&D there was a lot of tension between new players (both to the group, and D&D) and old players. It stemmed partly from oldbies not wanting their ball taken away, but also because I didn't want to be too harsh to the newbies.
I'm guessing this is fairly common theme when introducing new players to a group. I'm not to worried about the integration from a social aspect, as that can be resolved out of the game. I'm specifically asking how to handle new players making mistakes, and not killing them for it, and treating everyone equally. Should I even treat them differently?
This is the example of play that broke the group last time. I'd advised a new player that as a barbarian they should be engaging the enemy (a dire weasel), however it got an Attack of Opportunity and I rolled enough 20s to instakill the character. I didn't fudge the dice, for fear of upsetting the more experienced players who don't get that treatment. The player whose character died lost interest in RPGs altogether, and never returned.
How can I treat old and new players fairly, without upsetting anyone?