Inserting CD causes media players to play static

I use both Windows Media Player and iTunes to play music. Both work fine,
but lately when I insert a CD and open it in either player, all music whether
CD or compressed starts sounding poor - with static-like sounds added. When
I restart the computer the problem seems to disappear for music in the
library, but reappears again when a CD is inserted. The same thing happens
when I play CDs with multimedia features that play with neither media player
needed.