Validator generates invalid HTML

When the validator has a fatal error, the output does not conform to
HTML 4.01 (according to the validator). The output of the validator is:

http://validator.w3.org/check?uri=http%3A%2F%2Fvalidator.w3.org%2Fcheck%3Furi%3Dhttp%253A%252F%252Fwww.poptop.com%252F%26charset%3D%2528detect%2Bautomatically%2529%26doctype%3D%2528detect%2Bautomatically%2529&charset=%28detect+automatically%29&doctype=%28detect+automatically%29

for (this is a document without a document type declaration):

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.poptop.com&charset=%28detect+automatically%29&doctype=%28detect+automatically%29

-- 
						João Miguel Neves