Porsche: Defective Rear Windows in the Cayenne

I recently purchased a 2006 Porsche Cayenne. Twice in the last six
weeks that rear window spontaneusly cracked after using the rear
defroster.

The folks at Porche claim that this is not a common occurrance and have
refused to replace the window... and show little inclination to try to
solve the problem.

Has anyone had a similar exerience?

<net> wrote in message
news:googlegroups.com... 

Try

www.rennlist.com

They have forums devoted to specific Porsche models, including the Cayenne.

Porsche won't replace the window under warranty?