Problem with image upload in FCKeditor

Config.php is not the only thing that must be changed to enable the file browser.

If you get error message saying that file browser is disabled, re-check the following:

• In "Administer > User Management > Permissions" assign the
  "allow fckeditor file uploads" permissions.
• locate file named
  settings.php inside your drupal directory (usually sites/default/settings.php)
  and set $cookie_domain variable to the appropiate domain (remember to logout and login again after doing this step).
• adjust the File browser settings for each profile (disabled by default)

Wiktor Walc
http://www.fckeditor.net
"Support Open Source Software"

Could you post the relevant parts of config.php that you changed?
That way I see if theres any problem.
I had the same issue but managed to fix it.
Basically, I just changed to this (and nothing else):

// SECURITY: You must explicitly enable this "connector". (Set it to "true").
// WARNING: don't just set "$Config['Enabled'] = true ;", you must be sure that only
// authenticated users can access this file or use some kind of session checking.
$Config['Enabled'] = true ; <--------- here

// Path to user files relative to the document root.
$Config['UserFilesPath'] = '/files/' ; <--------------here, I already have this folder

// Fill the following value it you prefer to specify the absolute path for the
// user files directory. Useful if you are using a virtual directory, symbolic
// link or alias. Examples: 'C:\\MySite\\userfiles\\' or '/root/mysite/userfiles/'.
// Attention: The above 'UserFilesPath' must point to the same directory.

$Config['UserFilesAbsolutePath'] = '/files/' ; <------------- same as above
require_once "../../../../../filemanager.config.php"; <----- added this from the readme.txt

(Be careful to put the above line right there and not under the previous $Config)

AND, finally, go to settings.php (/sites/default/settings.php), re-enable write permissions (of course do the same for folder 'default' and change back when done) and uncomment this line:
$cookie_domain = example.com <---------
Remember to change example.com to read your site. <-----

Hope this helps. But meanwhile, IMCE works perfectly instead to load your images while you wait to fix your issue. Though you should not take the shortcut.
Please check out http://kenyatrail.com (Still under construction) and critique before I go too far.

I had trouble trying to configure the image upload feature.

I resolved the issue in a roundabout way:
Visit http://kyemba.net/uploadguide.htm

OK, apologies if this answer is not what you're looking for, but I just got the insert/edit image to work for me. I have drupal 6.12, fckeditor 2.6.4, and the Image module.
1. Installed fckeditor module, also fckeditor, and the Image module.
NOTE: My default image path at (/admin/settings/image) is images. I ftped some images to my images folder.
1. Did everything in the modules/fckeditor/readme.txt *Configuration* section.
2. Did everything in the modules/fckeditor/readme.txt *How to enable the file browser* section.
3. Cleared my cache (admin/settings/performance).
4. Created a new story, clicked on the image icon on the fckeditor toolbar, clicked on browse server, but nothing was there, even though I knew I had ftped some images! Turned out I needed to make 1 more change.
5. Back to the (editor/filemanager/connectors/php/config.php)
/* Configuration settings for each Resource Type These were wrong - were set to image instead of images.
$Config['FileTypesPath']['Image']= $Config['UserFilesPath'] . 'images/' ;
$Config['FileTypesAbsolutePath']['Image']=($Config['UserFilesAbsolutePath'] == '') ? '' : $Config['UserFilesAbsolutePath'].'images/' ;

6. Cleared the cache.
7. Worked! Insert and upload now goes to the right folder.
:)

I still have the same problems. But found that sites\all\modules\fckeditor\filemanager.config.php does not exists.
What to do?