Hey, I had a similar problem on Mandrake 9, which I have just sorted thanks to 2 guys.
The main problem I had was Plug N' Play OS set to "yes" in the bios... changed that and Mandrake worked like a dream.
Also... in KDE Control Center in "System" there is a sound configuration option there. Put the I/O sound device thing to "Auto Detect" and check you don't have full-duplex or something like that ticked. Play around with it.... it'll work eventually.
Here's a link to the questions and answers I had, I hope its of use.