Underbody Shield problems of the 1997 Toyota RAV4

We took our 1997 Rav4 to the mechanic for a routine tire rotation and oil change. The mechanic informed us the subframe was severely rusted and dangerous to drive. I did some research on the problem and found out it is a common occurrence with all Rav4's and that Toyota refuses to accept responsibility for a major design flaw in these vehicles. I've never heard of this happening in other vehicles I've owned. My mechanic whom I trust implicitly said they've replaced many sub frames on these vehicles exclusively.

I took my vehicle in for some routine maintenance to be done and was called to come in by the mechanic. He showed me under my car, more specifically the frame on my car. It had extensive rust damage. The rust was not just on the surface, but had large holes eaten away within the entire frame. The body of the vehicle is in very good condition. The mechanic stated it was not safe to drive, because of the holes/damage on the frame. He did not think it was normal wear. Updated 10/20/11.