Honestly, you're not going to like this response - but it's the best possible advice that can be given:
You're always going to have some major or minor issue or complaint with PSX to PSP execution as long as you stick with 3.90.
As much of a pain as it might sound, you really need to downgrade to 3.71m33-3. That's 3.71m33-3.. not 4 or 5.
All your stability, sound, multiple eboot dumping-emulating-kernel-popping-blahblahblah1.5-3.71-3.80-3.whatever will vanish.
3.71m33-3 is the safest bet to be sure of it all.
hope that didn't sound too sarcastic.
