Here's the problem on a client WP install & particulars:
Bluehost, running WP2.6.1.
Initial WP install was done via Fantastico.
Upgraded to WP2.6.1 using WPAU plugin (today).
The problem existed before the upgrade to 2.6.1. Upgrade did not change anything in regards to problem.
We can upload an image, but if you try to insert it into a post, you get a blank screen (both flash or browser method).
In IE7, there is a error message in the browser status bar, when clicked on this is the message:
Error: Object doesn't support this property or method
URL: http : // client url/wp-admin/media-upload.php?type=image&tab=type&post_id=150
I have tried the list of things on Otto's great thread on Image/Media Uploader problems with no results.
Also, tried another suggestion that included deleting /wp-includes/js directory and reinstalling with fresh code.
Also, deactivated all plugins, still same problem.
Any ideas or suggestions are greatly appreciated.