''dc swat'' please help

[grover29]

only that games working good at my dreamcast

zombie revenge
sega rally
quake 3 areana
mortal kombat gold but boot game from sd or game disk dosent matter
(game videos endings always skipping)

street fighter 3th impact

18 wheels of steel haulin

silent scoope

but
resident evil 3, code veronica,f355,hause of dead 2

thats all 4 games always freezing during at game dosent matter what ever you use orginal disk backups or sd loader with dreamshel with optimized gdi or optimized iso

does not change the problem same thing happen everytime

i just want know what kind problem have my dreamcast how i can fix ?