slideshow problems

have tried to add different slideshows to my page with – nextgen-gallery get – Error 500 – Internal server error – same with – flash album gallery, with – super slideslider gallery the thumbnails do not appear the images remain full size under each other but under the images appears a list which i assume are the thumbnails that should appear, with slideshow-gallery no thumbnails appear at all – am on a 1and1 linux server.. anyone has a clue what is going on?