Can a theme make Firefox crash?

New WPMU 2.7.1 install with only one blog. I installed the wpmu-dixi theme and played around with the configuration. Uploaded a new header image, changed the sidebar widgets a little, and changed the copy on the About page. Then I tried to add my first Post. As soon as I press the "Add Media" button Firefox crashes. I have never seen Firefox crash like that before.

I tried exactly the same thing with Google Chrome and it worked properly - I wrote my Post and inserted an image with no problems.

Then I switched back to Firefox and it crashed again exactly the same way.

I have another WPMU 2.7.1 system with different themes (no wpmu-dixi) and I don't have any problems using Firefox.

My Firefox is 3.0.10 running on Windows XP Pro.

Here's the content of wp-content/mu-plugins/:

additional_tags.php                  forums-framework.php
admin-footer-text.php                login-image.php
admin-message.php                    readme.txt
all-in-one-seo-pack                  remember-me-checked.php
all_in_one_seo_pack.php              remove-permalinks-menu-item.php
avatar-comments.php                  remove-wp-dashboard-widgets.php
avatar-posts.php                     simple-sitemaps.php
avatars.php                          widget-avatar.php

Will try this later tonight on a different system. Very odd.