2.7’s built-in gallery settings

I’m having trouble with the built-in gallery feature, which has always treated me very kindly on previous versions of WP, but with 2.7 it’s misbehaving.

I upload a number of images, give them all titles and captions as usual, save all the changes, change the display order, but then the new ‘Gallery Settings’ feature at the bottom of the media iframe does nothing at all. Clicking on the ‘add gallery’ button does nothing – it doesn’t add a gallery, it doesn’t make the iframe go away. So, I close the iframe and manually add the shortcode for a gallery: [gallery]. However, the gallery settings default is for thumbnails to link to the attachment page. I don’t want the thumbnails to link to the attachment page! I want them to link to the files (because I intend to use the lightbox plugin), or even better, I want the option of not having them link to anything – just display as thumbnails. But even though I have a ‘link to files’ radio button, I can’t get it to do anything because the ‘insert gallery’ button does nothing, and that’s the only button I have. There’s no ‘update gallery’ button, even once I’ve checked the radio button, I can’t do anything.

Question 1: why is this happening and what can I do about it?
Question 2: if I have to live with the settings control panel not doing anything, how can I change the settings manually? I went into phpmyadmin and searched through the wp_postmeta table (and others), but there’s an overwhelming mass of stuff there and I can’t see anything obvious that I can change.

Help!

Thanks!