Original Star Wars & ProLogic II

I’ve been playing around with my receiver’s upscaling features, so I popped in the original Star Wars trilogy DVDs and upscaled them. The picture looks good BUT the surround is off.

I did most of the testing with Empire & Jedi as the first one had bad surround IMHO. My old receiver did ProLogic and they sounded great but my new one has ProLogic II and they sound messed up. Sounds/voices popping in and out of the surround channel.

I also tested out the SE LaserDiscs and same prob, then the first LD pressings of the non-SE and it’s STILL THERE! The only decent decoding I could get was off the first LDs using the digital track but though the analog outputs. All other LDs with ProLogic work fine w/ optical out. Anyone have a clue what is going on?