There is a problem with starfox with 1.5, In the rom settings tab for PJ make sure the 'Memory Protection' is on "Protected Memory", there is no problem with RSP/Dsound you just need to change the RDB so it is correct... I'm pretty sure 1.5 shipped with this flag set incorrectly
You may need to replay the game for the changes to take effect properly, if you just change this and load a save state I'm pretty sure it won't work.. (when you load a state it's already feked up!)
This is one of the more lesser known issues.. it's very hard to recreate so it may or may not solve your problem I am not sure, I can only speak from the experience I've had with this issue