1. Try deleting the gta_sa.set file in your GTA San Andreas User Files folder.
2. If you got any d3d9.dll in your GTA directory, delete it.
3. Create a new user on Windows, and then run your SA-MP.
if that doesnt work change your samp version to (( sa-mp-0.3.7-install.exe )) Download it from here http://files.sa-mp.com/