diff --git a/YACReaderLibrary/db/treemodel.cpp b/YACReaderLibrary/db/treemodel.cpp
index a55009bb..d403eba8 100644
--- a/YACReaderLibrary/db/treemodel.cpp
+++ b/YACReaderLibrary/db/treemodel.cpp
@@ -255,7 +255,9 @@ void TreeModel::setupModelData(QSqlQuery &sqlquery, TreeItem *parent)
 
 		item->id = record.value("id").toULongLong();
 		//la inserción de hijos se hace de forma ordenada
-		items.value(record.value("parentId").toULongLong())->appendChild(item);
+		TreeItem * parent = items.value(record.value("parentId").toULongLong());
+		if(parent !=0)
+			parent->appendChild(item);
 		//se añade el item al map, de forma que se pueda encontrar como padre en siguientes iteraciones
 		items.insert(item->id,item);
 	}
diff --git a/YACReaderLibrary/library_creator.cpp b/YACReaderLibrary/library_creator.cpp
index 76a563dd..8ee77109 100644
--- a/YACReaderLibrary/library_creator.cpp
+++ b/YACReaderLibrary/library_creator.cpp
@@ -427,6 +427,12 @@ ThumbnailCreator::ThumbnailCreator(QString fileSource, QString target="", int co
 void ThumbnailCreator::create()
 {
 	QFileInfo fi(_fileSource);
+	if(!fi.exists()) //TODO: error file not found.
+	{
+		_cover.load(":/images/notCover.png");
+		return;
+	}
+
 	if(fi.suffix().compare("pdf",Qt::CaseInsensitive) == 0)
 	{
 		Poppler::Document * pdfComic = Poppler::Document::load(_fileSource);
diff --git a/YACReaderLibrary/library_window.cpp b/YACReaderLibrary/library_window.cpp
index 5ecacd10..bd2ccda3 100644
--- a/YACReaderLibrary/library_window.cpp
+++ b/YACReaderLibrary/library_window.cpp
@@ -1229,6 +1229,12 @@ void LibraryWindow::removeLibrary()
 	{
 		deleteCurrentLibrary();
 	}
+
+	if(libraries.size()==0)
+	{
+		disableAllActions();
+		showNoLibrariesWidget();
+	}
 }
 
 void LibraryWindow::renameLibrary()
@@ -1478,17 +1484,20 @@ void LibraryWindow::closeEvent ( QCloseEvent * event )
 
 void LibraryWindow::showNoLibrariesWidget()
 {
+	disableAllActions();
 	mainWidget->setCurrentIndex(1);
 }
 
 void LibraryWindow::showRootWidget()
 {
+	enableActions();
 	libraryToolBar->setDisabled(false);
 	mainWidget->setCurrentIndex(0);
 }
 
 void LibraryWindow::showImportingWidget()
 {
+	disableAllActions();
 	importWidget->clear();
 	libraryToolBar->setDisabled(true);
 	mainWidget->setCurrentIndex(2);
diff --git a/images/notCover.png b/images/notCover.png
index 669dca68..bbd7936b 100644
Binary files a/images/notCover.png and b/images/notCover.png differ