Recently i have had loads of adverts poping up in internet explorer. Most of the adverts seem to be relevant to the page i'm on. for example: if i went on an mp3 site then the adverts would be about mp3 offers etc. But the sites i go on never used to have pop up ads on them but they do now. i read somewhere that i could have a parasite installed on my pc without me knowing. so does anyone know how i can detect and remove such parasites? And off the subject: my pc has been crashing much more than it has ever done before recently. can anyone give me some things to check for on my pc please?