Web Robot reaches unexpected HTTP state

While running web-robot (5.2.8) on some web sites it terminated with the
error
'Bad HTTP state (state number) '

Termination is forced by the HTDEBUGBREAK in http.c (line 1286), anyone
knows how to avoid this problem ?

command line used:

webbot -vu -depth 5 -single -prefix http -ss -include
"\.html$|\.htm$|\.zip$|\.gz$" -saveimg http://www.miningco.com

Any help appreciated.