I put in ufku's fix for this problem: http://drupal.org/node/817824 And that causes the file browser to appear correctly now. But I am also getting a SQL error when I attempt to update a node, when I don't upload an image.

user warning: Column 'field_hdr_img_imceimage_width' cannot be null query: UPDATE content_type_primary_landing SET vid = 29, nid = 26, field_action_value = '<br />\r\n', field_action_format = 2, field_hdr_img_imceimage_path = NULL, field_hdr_img_imceimage_width = NULL, field_hdr_img_imceimage_height = NULL, field_hdr_img_imceimage_alt = NULL, field_resources_value = '<br />\r\n', field_resources_format = 2, field_solutions_value = '<br />\r\n', field_solutions_format = 2, field_vid_pl_fid = 57, field_vid_pl_list = 1, field_vid_pl_data = 'a:1:{s:11:\"description\";s:0:\"\";}' WHERE vid = 29 in C:\WWW\onvia\sites\all\modules\cck\content.module on line 1213.

For now I'm going to modify the DB field to accept null values - which I think should fix it.