Image not uploading. Stuck at spinning icon.

Do you have this issue in all browsers?
If only in opera then you may have the old version of drupal's misc/jquery.form.js
try replacing it with http://jqueryjs.googlecode.com/svn/trunk/plugins/form/jquery.form.js

I'm also having having this issue on one specific site, be it using Firefox or IE. The uploading status message is shown, the button shows the spinning icon but I don't get any validation / end message, it just keeps looping.

When I eventually just refresh the page, I see that the image has actually been fully uploaded, but I still need this to work properly.

Deleting / browsing works fine, and I have 777 set on the folders being used.

Any ideas?

UPDATE: actually, now I'm consistently getting a JS error in Firebug:

missing ) in parenthetical
uploaded." ] } }<div class="dev-timer"> ...own()=<strong>47.48</strong> MB.</div>);
http://www.whatever.com/misc/drupal.js?a
Line 193

Which is happening here on the return line of this function:

/**
 * Parse a JSON response.
 *
 * The result is either the JSON object, or an object with 'status' 0 and 'data' an error message.
 */
Drupal.parseJson = function (data) {
  if ((data.substring(0, 1) != '{') && (data.substring(0, 1) != '[')) {
    return { status: 0, data: data.length ? data : Drupal.t('Unspecified error') };
  }
  return eval('(' + data + ');');
};

OK, I figured out what is causing this in my case: the Devel module is appending extra data in the JSON response string and botching it up. As soon as I disabled Devel, the file upload worked perfectly. This comment shows a similar case but involving Devel clashing with the default upload module.

Since I need Devel on the dev server, I'll try to find a way to disable it on specific pages for now. If the latest version at this time (1.17) of that module still has this issue, I'll report it there.

Thanks tirdadc, disabling the Devel module fixed this issue for me as well. I was worried I was going to have to try a different WYSIWYG editor and such, but this solved it. Thanks again.

Devel was the prob for me too. Thanks @tirdadc