Default action for opening drive been set to MP3Tag

hello all,

I used this womderfull program before with no troubles(older version on older machine)

but since i recently installed it it gives me a weird problem which i cant resolve.

version 2.40
OS WinXP SP2

installing goes fine, no problems there

after installing when i click on a drive root eg c:...... mp3tag gets opened.

this all doesnt happen when i deselect 'explorer shell extension' during install.
but then i cant use the shell extension, what i really liked and used most of the time, rather then first opening the program and then adding files.

if anyone has suggestions id like to hear them cause im at a total loss here