i got that problem too all i did to fix it was first check my gta.dat if it was fail but the settings was:
#
# Load IDEs first, then the models and after that the IPLs
#
IMG DATA\PATHS\CARREC.IMG
IMG DATA\SCRIPT\SCRIPT.IMG
IMG MODELS\CUTSCENE.IMG
SPLASH loadsc2
#
# Object types
#
IDE DATA\MAPS\generic\vegepart.IDE
IDE DATA\MAPS\generic\barriers.IDE
IDE DATA\MAPS\generic\dynamic.IDE
IDE DATA\MAPS\generic\dynamic2.IDE
IDE DATA\MAPS\generic\multiobj.IDE
IDE DATA\MAPS\generic\procobj.IDE
IDE DATA\MAPS\LA\LAn.IDE
IDE DATA\MAPS\LA\LAn2.IDE
IDE DATA\MAPS\LA\LAs.IDE
IDE DATA\MAPS\LA\LAs2.IDE
IDE DATA\MAPS\LA\LAe.IDE
IDE DATA\MAPS\LA\LAe2.IDE
IDE DATA\MAPS\LA\LAw2.IDE
IDE DATA\MAPS\LA\LAw.IDE
IDE DATA\MAPS\LA\LAwn.IDE
IDE DATA\MAPS\LA\LAhills.IDE
IDE DATA\MAPS\LA\LAxref.IDE
IDE DATA\MAPS\SF\SFn.IDE
IDE DATA\MAPS\SF\SFs.IDE
IDE DATA\MAPS\SF\SFse.IDE
IDE DATA\MAPS\SF\SFe.IDE
IDE DATA\MAPS\SF\SFw.IDE
IDE DATA\MAPS\SF\SFxref.IDE
IDE DATA\MAPS\vegas\vegasN.IDE
IDE DATA\MAPS\vegas\vegasS.IDE
IDE DATA\MAPS\vegas\vegasE.IDE
IDE DATA\MAPS\vegas\vegasW.IDE
IDE DATA\MAPS\vegas\vegaxref.IDE
IDE DATA\MAPS\country\countryN.IDE
IDE DATA\MAPS\country\countN2.IDE
IDE DATA\MAPS\country\countryS.IDE
IDE DATA\MAPS\country\countryE.IDE
IDE DATA\MAPS\country\countryW.IDE
IDE DATA\MAPS\country\counxref.IDE
IDE DATA\MAPS\interior\int_LA.IDE
IDE DATA\MAPS\interior\int_SF.IDE
IDE DATA\MAPS\interior\int_veg.IDE
IDE DATA\MAPS\interior\int_cont.IDE
IDE DATA\MAPS\leveldes\levelmap.IDE
IDE DATA\MAPS\leveldes\levelxre.IDE
IDE DATA\MAPS\interior\gen_int1.IDE
IDE DATA\MAPS\interior\gen_int2.IDE
IDE DATA\MAPS\interior\gen_intb.IDE
IDE DATA\MAPS\interior\gen_int3.IDE
IDE DATA\MAPS\interior\gen_int4.IDE
IDE DATA\MAPS\interior\gen_int5.IDE
IDE DATA\MAPS\interior\savehous.IDE
IDE DATA\MAPS\interior\stadint.IDE
IDE DATA\MAPS\leveldes\seabed.IDE
# interiors
IDE DATA\MAPS\interior\props.IDE
IDE DATA\MAPS\interior\props2.IDE
IDE DATA\MAPS\interior\propext.IDE
# vehicle upgrade models
IDE DATA\MAPS\veh_mods\veh_mods.IDE
# txd parents
IDE DATA\TXDCUT.IDE
# have to load map.zon before any of the IPLs
IPL DATA\MAP.ZON
# IPL DATA\NAVIG.ZON
IPL DATA\INFO.ZON
#
# Scene information
#
SPLASH loadsc2
IPL DATA\MAPS\LA\LAn.IPL
IPL DATA\MAPS\LA\LAn2.IPL
IPL DATA\MAPS\LA\LAs.IPL
IPL DATA\MAPS\LA\LAs2.IPL
IPL DATA\MAPS\LA\LAe.IPL
IPL DATA\MAPS\LA\LAe2.IPL
IPL DATA\MAPS\LA\LAw.IPL
IPL DATA\MAPS\LA\LAwn.IPL
IPL DATA\MAPS\LA\LAw2.IPL
IPL DATA\MAPS\LA\LAhills.IPL
IPL DATA\MAPS\SF\SFn.IPL
IPL DATA\MAPS\SF\SFs.IPL
IPL DATA\MAPS\SF\SFse.IPL
IPL DATA\MAPS\SF\SFe.IPL
IPL DATA\MAPS\SF\SFw.IPL
IPL DATA\MAPS\vegas\vegasN.IPL
IPL DATA\MAPS\vegas\vegasS.IPL
IPL DATA\MAPS\vegas\vegasE.IPL
IPL DATA\MAPS\vegas\vegasW.IPL
IPL DATA\MAPS\country\countryN.IPL
IPL DATA\MAPS\country\countN2.IPL
IPL DATA\MAPS\country\countrys.IPL
IPL DATA\MAPS\country\countryE.IPL
IPL DATA\MAPS\country\countryW.IPL
# interiors
IPL DATA\MAPS\interior\int_LA.IPL
IPL DATA\MAPS\interior\int_SF.IPL
IPL DATA\MAPS\interior\int_veg.IPL
IPL DATA\MAPS\interior\int_cont.IPL
IPL DATA\MAPS\interior\gen_int1.IPL
IPL DATA\MAPS\interior\gen_int2.IPL
IPL DATA\MAPS\interior\gen_intb.IPL
IPL DATA\MAPS\interior\gen_int3.IPL
IPL DATA\MAPS\interior\gen_int4.IPL
IPL DATA\MAPS\interior\gen_int5.IPL
IPL DATA\MAPS\interior\stadint.IPL
IPL DATA\MAPS\interior\savehous.IPL
# level design
IPL DATA\MAPS\leveldes\levelmap.IPL
IPL DATA\MAPS\leveldes\seabed.IPL
IPL DATA\MAPS\paths.ipl
IPL DATA\MAPS\paths2.ipl
IPL DATA\MAPS\paths3.ipl
IPL DATA\MAPS\paths4.ipl
IPL DATA\MAPS\paths5.ipl
IPL DATA\MAPS\cull.ipl
IPL DATA\MAPS\tunnels.ipl
IPL DATA\MAPS\occluSF.ipl
IPL DATA\MAPS\occluveg.ipl
IPL DATA\MAPS\occluLA.ipl
IPL DATA\MAPS\occluint.ipl
IPL DATA\MAPS\audiozon.ipl
#
# Interiors
#
SPLASH loadsc4
if it dont work then reinstall gta sa but you must use the version
1.0 so download the patch to downgrade thanks for me