Tire Blowout problems of the 2007 Toyota Camry Hybrid

I purchased 4 brand new tire's, continental contiprocontact, p215/60 r 94 t, at mavis discount tire in January of 2010. After three months, and approximately 3,000 miles, one tire blew out due to a sidewall explosion. This tire was the rear passenger tire. This tire was replaced by the dealer at a nominal cost, since I had purchased insurance on the tires. Exactly one month later, the front driver tire blew out from the same cause, and this failure occurred while driving on the highway (the first tire failure was also a highway failure). This failure was also inside the side wall, and not due to debris or pothole. This makes two of four new tires experiencing dangerous highway failure within the first 4,000 miles of ownership. This 50% failure rate without explanation I feel is a sign of a manufacturers performance defect, given both failure occurring at highway speed, and when the tires where in new condition.