Windshield problems of the 2005 Nissan Quest

I was accelrating onto an interstate highway when my windshiield cracked. There was no reason for this since no other vehicles were in the vicinity of my vehicle and the vehicle was new (1500 miles). I reported a stress fracture to the dealership where the vehicle was purchased and to the Nissan corp. Everyone I spoke with said something hit the glass and refused to correct the problem. There was no evidence of anything hitting the glass. My mechanic and an insurance investigator agreed with me. The problem remains unresolved.