No character encoding warnings and error on pages previously validated pages

NOTE: Whenever possible, give the address of the document you were
checking.
In the past two days when validating Web Pages I, on occasion get a message
that states I have one error and 3 warnings that state I had no character
encoding.  What is interesting is that when I run Web pages previously
validated I got the same message and when trying later the programs will
validate.  Is there a glitch going on or is there something I am doing that
is causing this message.  I never had this problem before.  It began
yesterday morning but last night the pages validated, but again this
afternoon I am getting the same message.