unwanted favourites

after booting pc in my favourites list i keep getting unwanted files,folders & web sites i.e porn &health news. i have deleted and sent to recycle bin but they return sometimes even while i am still on the internet. how do i get rid of these for good?

Download, update and run both Spybot S&D and Ad-Aware (both in my sig).

Then download HijackThis, again in my sig, run a scan, save your log and copy and paste it in your next reply.

Also a virus scan wouldnt hurt.