2007 Toyota RAV4 seat belts problems

On july 20, 2010 I was driving my 2007 toyota rav4 when I was hit by another car at a high rate of speed. My seat belt failed to restrain me and I hit my head, requiring stitches and a cat scan. My car is currently at a collision center waiting to be evaluated. I have not previously had any incidents where my seat belt had a reason to restrain me, so I do not know if this is an isolated incident or a possible seat belt defect.

I was driving on a dirt road around 25-30 MPH when my drivers side curtain shield airbag (csa) deployed unexpectedly. Previous to deploying, the seatbelt had suddenly locked into place. I leaned back to get the seatbelt to release, and as I tried to lean forward to see if it had, the airbag suddenly and unexpectedly deployed. I stopped the vehicle and looked around the car for damage from a collision and observed none. I also did not feel or sense a collision happening.