old lady needs help!

hi I seem to have this problem with my computer that I think has something to do with my son looking at things he shouldnt. I get these web sites that pop up ie: searchme.com,redorbit.com, an so on. even when i am not on the internet, these web pages still come up. i purchased stopsign scanner. and that wont even help out. and for some reason my automatic updates are turned off and I cant turn them on. I just get this message that says" we're sorry. the security center could not change tour automatic update settings. to try changing these settings youself, go to system control panel on the automatic update tab, select automatic(recommended) then click ok". so I do that and the same message pops up. please help me fix this. I have windos xp home edition version 2002 and a dell dimension DIME521 amd Sempron(tm) processor 3400+ 1.80ghz,960 mb of ram

 

sound to me like spyware and a huge problem with spyware also try to download spybot search and destroy and do a scan and find the little programs that are giving you trouble (i used stop sign scanner before and it just scans the computer and never removes them download avast home edition to do a virus scan just to be on the safe side