Adam Engst, founder of tech newsletter TidBITS, has said that he believes computers become slower with age, a process which can't be reversed with a reinstall or such, in other words, the hardware changes.
Last week I fished out two laptops, both like 5-7 years old. (They've been keept snug and dry.) And they both sort of didn't work. There was just odd things going on, like they refused to connect to the networks though they could see them, or the external DVD drive did not work with them. It just felt like machines on the brink of death. You know how you can sense that sometimes? When I was young, I once sold a used bike. I had been pretty much used. Everything worked on it, but just the whole feel of the bike said to me it was working on it's last breath. And true enough, shortly after the sale, it just broke down all over, and never was used again. (I think I later offered him his money back, but I'll try and make sure.)
Now, back to computers, I can understand a battery getting old or dying, because it is chemical in nature. But the other parts in a computer, why would they get old? (It seems to apply more if the machine is not used.) They are plastic, metal, and silicone. Not, so far as I know, materials which deteriorate quickly, outside of damp or extreme temperatures. So...
For me emotionally, computers should be like Charles Babbage said of his mechanical computer the Difference Engine: "It does not make errors. Either it works or it doesn't at all." There should be no odd grey-area or weird on-and-off malfunctioning. But there is. I guess they are just so complex that this stuff "develops" somehow.