[Dx4win] Computer CW Keying Problem

[EFL]

I've been using DX4WIN to send cw for years via a parrallel port (LPT) and it works great.  Today when I tried sending cw, I heard the cw clearly through my computer's speakers, but it sent one solid, continuous cw tone to the radio (Kenwood TS-850).  The tone would continue until I restarted the computer.  When I then restarted the computer and DX4WIN and began trying to send cw, the same thing happend. CW ok on the computer's speakers, solid unstoppable cw tone to the rig.  I tried another cable and had the same results.  

I also tried sending cw use my straight key and the rig worked perfectly.

Any suggestion how to solve this problem?

Thanks and 73's
Fred KF9YL