Philip,

Be sure that the switch next to the mic/line in on the back of the keyboard is set to mic. The switch is right next to the mic jack.

Now, lower the mic's volume to about 30 percent using the small volume control knob on the back of the keyboard, and do all mic adjustments using the electronic slider control found on the keyboar's screen. This will help.

It sounds as if you are overdriving the computer's sound card. Lower the computer's mic recording level to about 25 percent and this should be sufficient to aleviate the problem. If not, then it's an impedience mismatch problem, which may require the use of a pre-amp/mixer.

Hope this helps,

Gary