Why does my page that previously validated not validate now NO Changes were made

Hi,

Why does my page that previously validated not validate now NO Changes
were made.
It's been a year or so since I used the validator have the rules
changed? 
I don't like the messages they don't give any useful info.
Thanks,
I really try to make things standards compliant so I need help in
deciphering these error messages.
Thanks again,
Marie
NOTE: Whenever possible, give the address of the document you were
checking.
http://www.shorecollaborative.org/  this is the page I am trying to
validate

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