The DR-DOS/OpenDOS Enhancement Project

Hello!
My intention is to use multitasking for playing mp3 in "background" (one task).

So, found soundcard and drivers, put Mpxplay (great prggy), some mp3 files, starts drdos without multitasker and voila, stuff works just enough good for me.
BUT(!) when I start drdos (lite) with multitasker, sound sounds :) like pink noise in intervals (shhhhhhhhh.... shhhhhhhhh.... shhhhhh)

My Q is - what to do? Anybody made similar instalation?

(on other task, and that'll be visible (forground) I want to put DOS programm which grabs signals from com (rs232) port and put datas into some file.)

Mabe someone has some other ideas, solutions, well I'm all ears/eyes... anything but windows please :) (well on windows stuff works, but as all windows things ... and computer which I want to use is pretty old guy.

Thanks!