ad_w00000,

I had similar problems and found the solution based on some of the comments in drupal.org's imagecache module issues page. Take a look at my solution at http://drupal.org/node/139229 and see if it fixes your problem. My problem is in the .htaccess file in the "files" folder. I did not know until today that the files folder ALSO have its own .htaccess file!

Hope this helps.