One one of my blogs (all pretty much running the same set of plugins) I can no longer use the media-upload.php button because clicking it opens the upload frame as a page that replaces my post editor window. If I open it in a new tab, they are unrelated and I can't add the image to the post. I can't insert into the post at all, but I can see it in the media gallery after I save the changes, go back to my post, and then click the add image link again. Again, this works on all of my other sites on the same computer with the same browsers. It is not a browser-specific issue, either.
I re-downloaded 2.6 and replaced ALL of the files.
I disabled any plugins suspected of earlier errors.
I erased the js_cache folder contents.
Any insight would be most welcome because I am quite handicapped with this site at this point.
In case it will help any, my site in question is http://www.perfectlypetersen.com