What happend to my router? help!

unplugging router from power and pluuging it back fixed it, but i wanna know what happend.

i left my pc to dl, its dling forvalmost 50 hours or so, when i got back home all the lights in the router were on,
meaning ,1,2,3,4-i currently only using one pc so just one should be on. internet light on.
and on my moded, eathernet light is off.
i have linksys wrt54gl.
i know isp around here dont let you be online more then 3 days or so, could that be it? are the light indicator show that my isp disconected me? (for a static ip you need to pay extra so if you dont shut off you de facto have static ip). is it how routers crash usually?
this is my first router.
this is my first time dling for so long stright.

what do you think?

yea, torrent here too.
i dont realy mind it as it was after 50 hours, i usually dont dl more than 12 hour stright.
i just was out of the house so left it on.
thanks buddy