Your family appears to have contracted the deadly Repair-Resistant Renegade Appliance Virus (RRSAV). One of the mutations affects farming and gardening equipment exclusively.
Umm... Would that particular strain also infect chain saws? If so 'twould esplain why said device decided (albeit after two years of never being sharpened or having a chain replacement) to refuse to cut anything more solid than a stick. Of butter.
Wallyworld had a two pack of chains for only $5 more than the local dealer wanted for one chain, so when my site-to-store order comes in (probably today) I can finish off that tree that rested in repose during Sandy... (it's now in three piles - one of big chunks, one of smaller chunks, and one of branches of limited uselessness - a neighbor says he'll come over Saturday with his bucket loader and we can fill up the bucket with the branches and haul them out to the north forty and dump them where they can become one with the universe..and a shelter for tasty critters that fit on the plate next to the mashed potatoes.)
Lack of maintenance has nothing to do with it... ;-)