sgmllib.SGMLParseError: unexpected ':' char in declaration

[Alessio Pace]

I can't figure out how to solve this raised error in my application, I'm
trying to use the htmllib.HTMLParser, it usually works fine but in some
cases(I don't know why, I am processing hundreds of html texts, I will
debug eventually case per case later..) it raises this:

Traceback (most recent call last):
[......... ]
  File "Html2Txt.py", line 45, in convertToTxt          # my class Html2Txt
    parser.close()                  # close the htmllib.HTMLParser
  File "/usr/lib/python2.2/sgmllib.py", line 99, in close
    self.goahead(1)
  File "/usr/lib/python2.2/sgmllib.py", line 161, in goahead
    k = self.parse_declaration(i)
  File "/usr/lib/python2.2/markupbase.py", line 96, in parse_declaration
    self.error(
  File "/usr/lib/python2.2/sgmllib.py", line 102, in error
    raise SGMLParseError(message)
sgmllib.SGMLParseError: unexpected ':' char in declaration

Thanks if some one can help me, I am a newbie of python.