Im going to try to explain this the best i can, if you cant give me an answer, i thank you for trying. when i play a pttern on the sp 404 ready to add another sound, the sound i press stops on its own and doesnt play anymore, even when i have the gate and loop buttons off, has this happened to anybody before

is it a polyphony issue?
how many voices are playing and are they stereo?

its a deep violin sound that is in stereo, and when i try to add a hi hat once i start hitting the hi hat the violin sound stops

are there many other sounds playing at the same time?

if so then you may have exceeded the maximum voice limit
try resampling some stereo samples into mono

if it's only the violin and hats playing, then i am not sure what is causing the problem

if there's only the violin playing i would guess, turn off the loop on that sample.

make sure the "loop" light is not lit on the violin sample