Stanford POS tagger in Java usage

Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)
Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)
Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)
Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)
Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)
Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)
Mar 9, 2011 1:22:06 PM edu.stanford.nlp.process.PTBLexer next
WARNING: Untokenizable: � (U+FFFD, decimal: 65533)

These are the errors that I'm getting when I want to assign POS tags to sentences. I read sentences from a file. Initially (for few sentences) I'm not getting this error (i.e untokenizable), but after reading some sentences this error arises. I use v2.0 (i.e. 2009) of POS tagger and model is left3words.