Did you check your internet? Also network cable / network adapter if working properly or the drivers are good installed? Did you feel new noise from the desktop? It might be the harddisk being damage slowly
It goes like this on some games, download ... installl/copy .... download ... install/copy ... some games have lots of small files, games with huge cabinet files always download quicker ... this is normal
I have to agree with Dan Medved it's just my laptiop that does this my desktop does not do this and and it's not the laptop either because it will download everything else fine