I have tried to convert a tex file based on an IEEE example file which has a very long preamble (16,804 characters) before \begin{document}. Latex2RTF fails with an error message saying
"Error! Could not find <\begin|{|document|}> in 16000 characters Recompile with larger BUFFSIZE in getTexUntil() in parser.c"
Except BUFFSIZE is defined to be 200,000 characters in getTexUntil(). I believe the error message comes from getSpacedTexUntil() where BUFFSIZE is defined as 16,000. So I think the (straightforward) fix is to modify the error message in getSpacedTexUntil().
Also, could I suggest that the default buffer size is increased to 20,000?
could you please make the tex file available so that I can reproduce - and hopefully fix - the bug? (point to an url where to download, upload here, or send it to texconvfaq "at" gmx "dot" de )