filefront gave my a viris
i found another gta SA down grader patch on filefront for free link is:
http://files.filefront.com/GTA+SA+Downgrad...;/fileinfo.html
it should work properly because i used it to downgrade my game so i could mod(i have gta SA v.2 pc)
if this still don't work then unistall the game and reinstall and see what happenes then if it still does the same then go out to wal-mart,k-mart,toys are us etc and buy a legit copy of the game for between $8.99 - $17.99 then get the down grader patch from filefrontfilefront or gtagaming.com(i saw one there)and then you should have the ability to mod the game as u wish to without the error message your seeming to have(this is moslty why i don't trust sources such as direct2drive)
hoped i helped
p.s never try and weasel your way out of paying for a legit copy caz if you do then R* will hunt you down and kill you haha jk