Group Icon will not show after upload

my host updated their server - changed disks i guess -- now the icons for the group will not display - i upload a new icon for a group - i get no error message -- but image will not display

how can i fix this?

i tried unselecting imagecache then running upgrade.php - still no show -- i activate imagecache, but no luck

is there a cache folder I should empty? if so, whats the path to it?

please ....