Please forgive me in advance for a question which may very well be
misdirected.  After a bit of frustration developing for csound under
windows, I installed a dual boot of red hat linux on my machine.  

Here is the sticking point: whenever I try to launch csound to use a midi
input and a DAC output simultaneously, I get this error:

cannot reopen (null)

just after the usual "writing 2048-byte blocks of shorts to devaudio".  I
have tested /dev/sequencer using another application and it seems to work
fine.

Is this message being thrown up by csound, or by the operating system? what
does it mean? 

My apologies if this question is misdirected or too elementary.

Bill