i own a wk8 wich's allmost the same as wk6 but i've never experienced something like that however i use cakewalk to do my recording not the keyboard sequencer,i suspect something wrong with the operating system,make sur you have the latest one which is dated [June 28th, 2000]
,or dowload a new one for the GEM site and install it ,this could resolve your problem.
let us know what happens.
later
eddy