I used to have quite the problem myself playing in front of people, but only in certain circumstances. For instance, some joe sees my guitar and says oh yeah? what can you play. Then I was like, well this, and screw it up. Buddy was expecting a killer riff out of blue and that's hard when you're inexperienced. Now I just flat out refuse and say catch the band this weekend... If you're playing in a band in front of people it's alright, just get used to playing when drunk. Works for me (if it's liquor). Helps my stage appearence too and makes the groupies work harder.