swfupload上传大文件，报io错误！

郁闷，上传大文件报io错误！
  upload_url: "/handlers/mvideoUpload.ashx", // Relative to the SWF file, you can use an absolute URL as well.
                file_post_name: "resume_file",                // Flash file settings
                file_size_limit: "500 MB",
                file_types: "*.avi;*.flv;*.wmv;*.swf;*.rmvb;*.rm;*.mov;*.3gp;*.mpeg;",  // or you could use something like: "*.doc;*.wpd;*.pdf",
                file_types_description: "视频",
                file_upload_limit: "0",
                file_queue_limit: "1",                // Event handler settings
                swfupload_loaded_handler: swfUploadLoaded,                //file_dialog_start_handler: fileDialogStart2,
                file_queued_handler: fileQueued2,
                //file_queue_error_handler: fileQueueError,
                //file_dialog_complete_handler: fileDialogComplete,                //upload_start_handler : uploadStart, // I could do some client/JavaScript validation here, but I don't need to.
                upload_progress_handler: uploadProgress,
                upload_error_handler: uploadError2,
                upload_success_handler: uploadSuccess,
                upload_complete_handler: uploadComplete2,                // Button Settings
                button_image_url: "/template/blue/cannes/images/XPButtonUploadText_61x22.png", // Relative to the SWF file
                button_placeholder_id: "spanButtonPlaceholder1",
                button_width: 61,
                button_height: 22,                // Flash Settings
                flash_url: "/template/blue/library/js/swfUpload/swfupload.swf",                custom_settings: {
                    progress_target: "fsUploadProgress",
                    upload_successful: false
                },                // Debug settings
                debug: false