doesn’t sound right. if i had the cam in my hands I could probably figure out what’s wrong. Try the reset button to return to factory defaults and try manual mode again. Maybe the shutter speed is set so low that too much light is coming in? When you adjust the f-stop is it getting darker at all? gain low aperture small it should be underexposed.
OSX 10.5.8; MacBookPro4,1 Intel Core 2 Duo 2.5 GHz MacPro4,1 2.66GHz 8 core 12gigs of ram. GPU: Nvidia Geoforce GT120 with Vram 512. OS X 10.6.x; Camcorders: Sony Z7U, Canon HV30/40, Sony vx2000/PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.