Check out this advisory from Cisco that came out a couple days ago.  You need to read it and act on it immediately!  I’ll summarize for you : Thanks to a faulty clock signal component, certain Cisco devices will stop functioning after about 18 months and become really expensive bricks!  Reading through it, you’ll see phrases like “we expect product failures” and “is not recoverable.”  Seriously, what the hell? This really warms the heart.