have new philips x55 and noticed when i turn volume up near full i get feedback from the speakers and hear a high pitched noise.anyone have any suggestions or have similar problem?

Go into the volume control and mute the microphone. This _should_ only effect (or is it affect) playback using the microphone (you should still be able to record using the microphone).

If that doesn't work, let me know on here and I'll see if I can come up with something else.