Problems with serial ports (SER0: Interrupt 12 (2) cannot be requested)

Hello, I'm having trouble using COM1.

On my linux console (Debian squeeze) my user can redirect output to /dev/ttyS0 
without trouble. I control the device on the other side, and see the data coming 
in nicely.

When I start xdosemu, I try to do the same (dir >COM1), but it hangs there. 
Starting dosemu with -D9+s, I see these lines:

SER0: ret=0 queue=0
SER0: ret=0 queue=0
SER0: Read LSR = 0x60
SER0: ret=0 queue=0
SER0: tmp=0 int_cond=0 int_req=0 int=0 fifo=0
SER0: Read MSR = 0x0
SER0: ret=0 queue=0
SER0: INT14 0x3: Port Status, AH=0x60 AL=0x0
SER0: INT14 0x1: Write char 0x20
SER0: ret=0 queue=0
SER0: Func transmit_engine requesting TX_INTR
SER0: tmp=0 int_cond=2 int_req=0 int=2 fifo=0
SER0: Interrupt 12 (2) cannot be requested: enable=0 IER=0x0
SER0: tmp=0 int_cond=2 int_req=0 int=0 fifo=0
SER0: tmp=0 int_cond=2 int_req=0 int=0 fifo=0
...
<forever the last line>
...


I tried to set explicitly the comm parameters with 'mode COM1:9600,n,8,1' 
without success. Same syntoms.

I have $_com1 = "/dev/ttyS0" in my .dosemurc.

Can you help me here?

Best regards and thanks,
             Santiago.