Rear windows shattering suddenly was a common fault on R52 MINI Convertibles a few years back......BMW eventually found out internal stress faults in a batch of toughened glass manufactured before 2005 were responsible and replaced the complete hood assembly under warranty. If you buy an early R52 check it has been done as it can be an expensive repair.
11 pages of rear windows shattering on Mini2 forum:-
http://www.mini2.com...ware-fault.html
