You expect milk to go off. Or even beer. But small electronic components buried inside a machine shouldn't be a problem.
Sadly, that's not true... some of them, for various reason, have a limited life and when they expire it can be with pretty dire consequences :(
One of our work-horse machines (aka Citadel-III... the third such incarnation of the box) had started behaving erratically over the last few weeks and finally died. Not just problems starting... this was total death. Wouldn't even get to POST (Power On Self Test)
Opened it up to have a look and discovered the leakage from a bunch of capacitors. The leakage had managed to damage the motherboard beneath rendering the machine toast.
Turns out that it's not an uncommon problem as sites like BadCaps can testify. Hopefully the increased awareness and issues this is causing the likes of Dell will make motherboard suppliers a bit more careful (or responsible for shoddy components)... knowing about the problem soon enough to take remedial action would have saved a couple of days downtime and quite a bit of work...