Randowm shutdown [Generic Host for Win 32 errors]

OPXPApp.exe Error..... /Generic Host for Win 32 errors continually pop up and shutdown computer at random sometimes 5 minutes after tsartup sometimes 1/2 hour I have antivirus software and have followed alot of posts and methods nothing seems to work on this sytem Short of visiting a repair shop I need some kind of help from you computer gurus I am very ignorant of fixes but suspect from what I see that a worm has backpacked on a security update from Microsoft onto my computer I have closed certain ports as per suggestions http://forums.techarena.in/windows-xp-support/1167394.htm to no avail I am lost HELP!!!