Page 1 of Sound dips. Please help!

Watching the film Ali on my Toshiba SD220E I kept getting sound dips during the fight scenes. Whenever a punch was laid the background music/dialogue would dip right down to virtually nothing then come back up again. I tried changing the sound settings on the player menu but to no avail. I have noticed this also during `The man who wasnt there` but not as bad. My setup runs from the DVD player to my stereo amp and out to the speakers. My amp doesnt decode DTS or DD5.1 but surely this shouldnt cause me to get these dips. Never had this before, please help!!

Not sure if this will cure your problem (it was just a thought and I am not an expert) but sometimes my DD5.1 amp does things like that.....and for me the cure it to switch off and unplug my entire system at the wall. When I plug it all back in again everything works a-OK.

But thats probably just me.