error sometimes showing

Hi,

Has anyone noticed the following error sometimes appearing on pages - on page reload it disappears again and it just seems to come up on random pages now and again:

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Warning

Failed loading XML file.

Opening and ending tag mismatch: HR line 14 and BODY

Premature end of data in tag HR line 8

Premature end of data in tag BODY line 6

Premature end of data in tag HTML line 1

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Anyone got an idea what could be causing it? There's no point me posting a url because most of the time it doesn't appear - only now and again

Thanks