Failing with "unable to parse ..."

I am trying to run ddd on a FORTRAN code and when I step into a 
subroutine bigrfsph, it issues the following error:

bigrfsph_ (lat=0xbfffea10, lon=0xbfffea08, radius=0xbfffea18, 
be=0xbfffea28, bn=0xbfffea30, bv=0xbfffea38) at bigrfsph.f:24
unable to parse pathname-substitutions

This is ddd version 3.3.11 for powerpc-apple-darwin8.6.0

I looked into it a little and the pathname-substitutions feature was 
recently added to be flexible about source code paths. Any insight 
into this matter would be appreciated. More info:

In the .ddd/init file is listed the following line:

set pathname-substitutions \n\

I've looked at documentation that suggests a different syntax is 
required for this set command, but perhaps the init file is OK. It 
seems that the correct format for the command is:

set pathname-substitutions /old_dir /new_dir

to start debugging with source in the new_dir.

I just learned that when I manually execute the "set" command as 
above, then the program recovers and can debug normally.

Here's the kicker: the problem seems intermittent. I have no idea 
why. It was worse yesterday than today. I now cannot reproduce the 
above error. This error occurred earlier today.

Thanks to everyone for their help.

-Tony

-- 
Tony Mannucci
Supervisor, Ionospheric and Atmospheric Remote Sensing Group
  Mail-Stop 138-308,                     Tel > (818) 354-1699
  Jet Propulsion Laboratory,              Fax > (818) 393-5115
  California Institute of Technology,     Email > [email protected]
  4800 Oak Grove Drive,                   http://genesis.jpl.nasa.gov
  Pasadena, CA 91109