ctools with panels colon issue IIS
I've finally succeded in correcting this bug, by modifying directly the Panels module. I'll publish a patch on panel's forum on drupal's site. Here's the solution :

In the file /sites/all/modules/panels/plugins/display_renderers/panels_renderer_editor.class.php, you have to change get_url() function (line 505), replace this:

 $url = 'panels/ajax/' . $this-&gt;plugin['name'] . '/' . $command . '/' . $this-&gt;display-&gt;cache_key;


by this

 if (variable_get('clean_url', FALSE))
  $url = '?q=';

$url .= 'panels/ajax/' . $this-&gt;plugin['name'] . '/' . $command . '/' . $this-&gt;display-&gt;cache_key;


As you maybe know the problem is caused by cleans Url, so it works without the fix if u disable it. But if you want to keep cleans url, apply the fix, it forces all ajax requests to be without cleans urls

PS: Thank you to MPD♦ who deleted my previous answer where i put a link to azure forum which was a possible way to solve the problem.