Link and Image Windows Hang in Firefox

When inserting an image or link in a post using Firefox the popup window hangs with a half-full status bar. I’ve let go for 30 minutes, and it never finishes. The link or image is inserted fine, but I have to close the window in order to get it to go away. If I press ‘Cancel’ Firefox usually crashes.

The same functions work fine in IE.

Firefox 1.5
WP 2.0

Thanks in advance for any help,
Matt