In order to make your life (and ours for that matter) easier, here are three steps that might solve your problem without having to post a new topic.
1. Re-install MTA
2. Re-install GTA:SA
3. Run Antivirus
How to do a clean re-install? Deinstall your game and then make sure no relevant files remain on your computer. Then conduct a clean install of your game.Further action:
Read this topicNOTE: Proposing one of those steps as a solution is not acceptable given the fact that we'd expect everyone seeking help to have worked through those already.