An unhandled error occured

Security exception - value of $_GET['SMDownloadsFile'] = 'Referat af GF 30.05.2011.pdf' is in conflict with value restriction 'AlphaNumeric' and the following characters: .-_

Stack trace
#0 /customers/2/8/8/nyksjskak.dk/httpd.www/base/SMEnvironment.class.php(89): SMEnvironment::getValidatedValue('$_GET', Array, 'SMDownloadsFile', 'AlphaNumeric', Array)
#1 /customers/2/8/8/nyksjskak.dk/httpd.www/extensions/SMDownloads/Main.class.php(14): SMEnvironment::GetQueryValue('SMDownloadsFile', 'AlphaNumeric', Array)
#2 /customers/2/8/8/nyksjskak.dk/httpd.www/base/SMController.class.php(253): SMDownloads->Init()
#3 /customers/2/8/8/nyksjskak.dk/httpd.www/base/SMController.class.php(108): SMController->autoExecuteExtensions('Init')
#4 /customers/2/8/8/nyksjskak.dk/httpd.www/index.php(22): SMController->Execute()
#5 {main}