Crackling Music (Using a Laptop as a PA System)

[davidk65]

I have suddenly found a need to use my laptop, with extension speakers, as a portable PA system.
I started by trying to play a music CD, via extension speakers, plugged into my laptop. I rarely use the CD Drive for music and was taken a-back by the poor quality of sound. At first I thought it was the disc or the drive or the extension speakers that were causing the problem, but when I connected to BBC i player, the sound was great i.e. no crackling or distortion.
When I plug a microphone (that I know is OK) into the laptop I cannot get any sound out. Going into the various sound set up menu's the system recognizes the mic, the graphics show the mic responding to various levels of sound.
The Questions Are:
Is the sound card faulty, hence the noise?
If it is faulty could that be the reason for the mic not working?
Why are the sounds from BBC i player not affected?

Any Suggestions.

[sinderella]

i had this problem and bought a cheap usb sound card off ebay.
sounds lovely now