seems like they all started with cpu panic
WARNING: interrupt level 12 not serviced
according some bug reports in sunsolve interrupt Level "N" may refers to a device, like Level 5 indicates that the problem is probably that of a cdrom drive
Level 15 from reading several sunsolve reports seems to indicate that Interrupt Level 15 related to volume manager or some "disk" controller related problem.
Do you have any jbod or san storage connected recently to your box? Or installed any patches/firmware related to it in recent memory?
Maybe you should also escalate to sun.