why do i get page not responding all the time?

i have a compaq presario cq60, it is a year old and it is so slow,when i switch it on it takes 20 mins to load and i constantly get page not responding no matter which browser i use. i regularly clean my laptop with ccleaner spybot and run avg free anti virus.i havent even used half of my memory and have no photos or music loaded.ive run trojan programs but its clean andd ive updated all drivers.last night i put it back to factory settings and its still very very slow.....help!!! im getting very frustrated with it.