I replied the following in this thread
Okay, I don’t know if this is the be-all end-all solution, but it appears that WordPress has issues with the www. in front of the domain and doing cross-browser implementations. I was having this Insert Image issue on one of my client’s sites, although another client with the same exact install was working fine.
For example, I was logged into a client’s site using:
https://www.domainname.com/wp-admin/post.php?action=edit&post=28
And it wasn’t working to Insert Images. I caught an exception error in Firebug that looked like this:
uncaught exception: Permission denied to get property Window.send_to_editor
tb_show("", "[URL REMOVED FOR PRIVACY]", false)thickbox.js (line 230)
tb_init()thickbox.js (line 26)
e(Object type=click target=img currentTarget=a.thickbox)jquery.js (line 11)
e()
However, if I changed the domain to:
https://domainname.com/wp-admin/post.php?action=edit&post=28
It worked. It seems like there’s some kind of cross-domain issue and wordpress treats the domain different with the www in front of it. OR that might be MediaTemple, I’m not too sure (it was a one-click install on MediaTemple which automatically sets the url to https://domainname.com when it installs itself).
I’m not sure if it’s a Firefox issue because it worked fine in Safari and Camino for me.
[edit]
Just double checked, Camino automatically changes the domain to https://domainname.com even when I’m logged in and try to add the www. in front, but Safari and Firefox leaves the www. in front and then causes the blank white screen which may explain why it’s so hard to track down.
SO DOUBLE-CHECK WHAT YOUR WORDPRESS URL/BLOG URL IS IN YOUR “GENERAL” TAB UNDER “SETTINGS” AND MAKE SURE YOUR BROWSER URL MATCHES THAT.
ie. https://www.domainname.com or domainname.com