jittery sound when scrolling thru track view then loss of output 8.5 pe

this happened after installing ez drummer I uninstalled and problem still there..... win xp 2... firepods chained together..... asio....... core 2 quad 4 gigs ram ... also I open a project in 7 pe and the exact same thing happened...jittery sound when scrolling up and down in the track view then the sound cuts out all together until a reboot then problem starts all over