There was one time where the game literally forced me to. Dragon Age Origins somehow threw me into a random encounter with a massive army of Darkspawn, which was dependant on me finishing story quests to gain help from factions. I had explored the areas, but not finished the quests, so I still got the encounter...so it was essentially an army of highly leveled Darkspawn against 4 low-level guys with no means of replenishing health.
I tried fighting out of it. So many times. I must have sunk about 1.5 hours into that one encounter but I still couldn't win - it was genuinely impossible. Out comes the command console...
I felt guilty, but it had to be done.