I'm hoping someone can help me with this problem...OK.,I have an imac 21.5 and everytime I start my mac I have no sound until I plug my headphones into the back HP plug then I get my sound back.Does that sound weird or what? I thought it did and thats why I need some help in figuring it out, so please, if anyone can help me figure out why I have no sound when i start up, only to get it back on after I plug my headphones into the back headphones plug,Please tell me? Thank you.