Modification of non-creatable array value attempted

[Franco Galian <lists@lhs.com.ar>]

Hello,
I'm using MHonarc to convert an ezmlm mailing list archive, it's been
working ok for a lot of time, but now there's a problem that stops the
convert process:
Modification of non-creatable array value attempted, subscript -2 at /usr/local/libdata/perl5/site_perl/mhtxthtml.pl line 376, <GEN3519> line 27.
I've identified the e-mail that's causing this problem, it is a
multi-part message in MIME format.

I was using MH 2.5.14, and now that I got this problem I updated to MH 2.6.8.
I'v also tryed converting to a new directory, with the same result. 
Any ideas? I've searched the mailing list and there was only one mail
related (at least that is wat I've found) , but it was referred to a bug
of a very early version of MHonarc...
##
perl -V: Summary of my perl5 (revision 5.0 version 6 subversion 1)
configuration:
Platform:    osname=openbsd, osvers=3.0, archname=i386-openbsd
##

Thanks for all your help

Franco Galián