Intermittent bug in Validator?

Hi Folks,

This is weird!  This page:

     http://homepages.shu.ac.uk/~cmsps/DIW/week17.html

sometimes validates OK and sometimes gives this message:

     Line 47, column 14: there is no attribute "target"

     <a target="_blank" href="secretPage.php">scheme one</a>.</p>

I don't know all the ins and outs of XHTML but I think it's OK ...
and so does the validator sometimes.  Are there many hosts doing the
validation?  Can some be out of sync?

I last changed it at: Feb 22 19:52

It failed at: Tue Feb 22 19:53:31 GMT 2005

It passed at: Wed Feb 23 21:00:44 GMT 2005

thanks,
     Peter
------------------+-------------------------------------------
Peter Scott       | Faculty of ACES
Senior Lecturer   |   Sheffield Hallam University
p.scott@shu.ac.uk |     Howard Street
+44 114 225 4905  |       Sheffield S1 1WB      UK