I have alike problem: dozen of 404 errors in webmastertools like this:
http://domain.ru/ka...tino-akcia-trexkomnatnaja
http://domain.ru/Sa...e-novosti-za-oktyabr-2012
And there's not linkes to these pages from anywhere. Strange situation, cause i've lot's of pages with urls of different length, but not all of theme comes with error.