Well my cousin have the same problem,
https://nightly.multitheftauto.com/mtasa-1.3-rc-4058-20120504.exe Click There
To download the MTA SA 1.3 RC 4058-20120504
Just start it as Administrator Rights. and install it in your MTA SA Directory . Its mainly presents at C:\Program Files\MTA San Andreas 1.3
And Run your MTA as usual
Note :- Its an official MTA SA RC update
PS :- If you have slow PC , this not gonna work , you should meet the minimum requirements to play at Low Graphics.