The brakes squeal because of the way they're made. they are designed to be durable, take a lot of abuse, and last as long as possible, therefore the pad surface is large and the compostion of the friction lining has a high metal content. The squealing is just a by product, and yes it can be annoying. So far i have not heard of any real fixes for it other than driving like a maniac. sometimes the squealing can be worse due to the accumulation of surface rust in the friction lining of the pad. You could try having the brake pads changed but its likely that it'll happen again.