rundll32.exe using up 100% of CPU usage

hello guys,

my concern is about rundll32.exe. i surf the internet on a daily basis for about 3 hours a day using a dial-up access. my concern begins after about an hour of surfing when my internet speed really goes very slow all of a sudden. my isp seems ok, then a friend of mine told me to press ctrl+alt+del to open up the task manager. when i do this, i almost always see that rundll32.exe is using up to 98% of my cpu usage. this really bothers me because for all i know, the cpu should not be running at 100% much less consumed by just this one application… do i have a virus in my pc? if so, how do i detect, clean and prevent this from happening. any help would be very, very much appreciated! thanks in advance guys! best regards!

renz