This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
This is the portion of my XHTML file that doesn't validate: <table> <thead>GREEK TEXT HERE</thead> <tr> <td>...</td> <td>...</td> <td>...</td> </tr> <tr> <td>...</td> <td>...</td> <td>...</td> </tr> </table> Mind that I have set the encoding correctly.
Please have a look at the definition of the thead element in the HTML 4.01 Recommendation, it seems you confuse it with <caption>; the Validator complains here because you have to include <tr>/<td> elements in the <thead> element. The encoding problems in the Validator output are known and probably subject of another Bugzilla entry, so this would be invalid/duplicate.