Creative A500, but it's obviously not the speaker problem... as they work fine during the configuration test
My Creatives did the exact same thing, they worked during the test, all speakers front and rear, but I could never get anything out of the rear during games or music. They worked in XP, IIRC, though it's foggy now. I never got to the bottom of it. These speakers I had dated back to mid nineties and didn't do 5.1 - just 4 satellites and a sub. As soon as I hooked up the new Logitechs everything worked great. I could have been doing something wrong I guess. I only mention this because like yours mine worked during the sound card test utility but not elsewhere.