[linux-audio-user] Midi and computer freezing

Hi, After months of searching, have finally found my old midi to serial port cables. They seem to be working fine, i can play music back using aplaymidi --port 64:0 file.mid. But when i go into qjackctl to connect the input to jack, it abruplty causes the pc to hault. No keyboard response, no mouse. Nothing. I have to hard reset the computer. Not sure how to go about checking what goes wrong, probably should view some kernel logs or something, but have no idea where to start. The problem happens everytime i try and connect the input to something (Zyn, rosegarden, etc..) I am using ubuntu dapper drake, kernel 2.6.15-22 for i686. Using some rubishy Cmedia soundcard serial port. Connected to piano with random midi cables. Any help appreciated!