Help!!Strange audio problems with wdm drivers

I've been using Sonar for awhile and just recently had a strange problem.I'm running Sonar 2.2xl on a 1 ghz laptop under Win2K sp3(?) with an echo layla 24.
Basically when using wdm/ks drivers the audio stops playing but the bar/beat counter keeps running.This will happen alot,no matter where latency slider is set.Normally when audio dropouts occur I get the red dropout message and playback would stop. It doesn't seem like a dropout but like Sonar can't playback the files but keeps running.If I switch to asio drivers Sonar will playback fine. Obviously I can keep using asio drivers,but I like to change the latency setting without restarting Sonar.I uninstalled and reinstalled my soundcard's driver but problem persist.
This started in the last day or 2. I have been installing /removing various music software on my computer(Ableton Live demo,Sonar 4 demo and Logic 4.8 ).
Also all other music software runs fine with asio driver(does anything else use wdm/ks ??)