Slim Application Error

The application could not run because of the following error:

Details:

Message: iconv() [function.iconv]: Detected an illegal character in input string
File: E:\wamp2\www\biblio-web\home\classes\util.class.php
Line: 837

Stack Trace:

#0 [internal function]: Slim::handleErrors(8, 'iconv() [ #1 E:\wamp2\www\biblio-web\home\classes\util.class.php(837): iconv('CP1252', 'UTF-8', 'Determinantes d...')
#2 E:\wamp2\www\biblio-web\home\public\html\boot2\usu_bib_central\detalle_libro.php(26): util::mostrar_sql('Determinantes d...')
#3 E:\wamp2\www\biblio-web\home\public\html\boot2\usu_bib_central\bib_central.control.php(22): include('E:\wamp2\www\bi...')
#4 [internal function]: g_bib_central_publicacion('19079')
#5 E:\wamp2\www\biblio-web\home\vendor\Slim\Route.php(392): call_user_func_array('g_bib_central_p...', Array)
#6 E:\wamp2\www\biblio-web\home\vendor\Slim\Slim.php(1052): Slim_Route->dispatch()
#7 E:\wamp2\www\biblio-web\home\index.php(149): Slim->run()
#8 {main}