^ Yeah do that.
Press your right mouse button (Second mouse button) and select the "Properties" button. When the properties menu opens, select the "Compatibility" tab. Then check the square "Run as administrator". You can also set the programs "Compatibility mode" to "Windows XP service pack 2" (IF you are using Windows Vista or Windows 7). Then press OK and close the properties menu. Do this to both your SAMP and your GTA San Andreas programs for full effect.
Reinstall your gta san andreas, reinstall your samp, use the downgrader I linked earlier, do what I described above (Run as administrator).
It HAS to work or the problem is with your computer.
_________________
Insert fucking huge signature with embedded videos and desktop background size images here.