Gallery Problem with IE (changing # of columns)

Dear all,

I have a problem with the gallery in wordpress 2.7 when using IE7. If have set the amount of columns to 4, therefore 4 thumbnails should be shown in one row. In FF everything works perfectly. However, IE always only displays only 3 thumbs in a row, no matter what I do (e.g. downsize the thumbs). Setting the column count to 0 leads to the problem that whenever one opens a particular blog page there will be only 1 picture per row – therefore it is not an option. You can have a look at the blog at https://www.vivacolonia.net/wordpress

Does anyone know what to do such that IE7 also displays 4 thumbs in a row? Many thanks in advance for your help!