R help - Mar 2014 - "Error: attempt to apply non function" and reference classes

Hello,
Currently I'm using a reference class in my script to manage data
exporting.  Sometimes, when I run my script things will be progressing as
expected when (seemingly mysteriously) every method in the object will
return "Error: attempt to apply non-function".  Attempting to recreate
the
object will then result in a "non function" error message about the
initialize function, which I've also defined in the class definition.
Re-sourcing the file containing the reference class definition will then
fix the problem, i.e. all methods will work as expected.  Has experienced a
similar problem?  It doesn't appear to be caused with actual errors
produced by my script, so I'm not certain where to start looking.  Any
ideas?  Thanks for your time.

Dave Mitchell

	[[alternative HTML version deleted]]