Hello, i've had some problems with thickbox media window. It didnt want to show up on some computers, with slow internet connection. I've found the solution, and i want to suggest it to the WordPress core (Can't use SVN for that).
Open file /wp-admin/includes/media.php
find function media_buttons() { (line 349 on 2.8.3)
and the find
$out = <<<EOF
<a href="{$image_upload_iframe_src}&TB_iframe=true" id="add_image" class="thickbox" title='$image_title' onclick="return false;"><img src='images/media-button-image.gif' alt='$image_title' /></a>
<a href="{$video_upload_iframe_src}&TB_iframe=true" id="add_video" class="thickbox" title='$video_title' onclick="return false;"><img src='images/media-button-video.gif' alt='$video_title' /></a>
<a href="{$audio_upload_iframe_src}&TB_iframe=true" id="add_audio" class="thickbox" title='$audio_title' onclick="return false;"><img src='images/media-button-music.gif' alt='$audio_title' /></a>
<a href="{$media_upload_iframe_src}&TB_iframe=true" id="add_media" class="thickbox" title='$media_title' onclick="return false;"><img src='images/media-button-other.gif' alt='$media_title' /></a>
EOF;
and change it with `$out = <<<EOF
<img src='images/media-button-image.gif' alt='$image_title' />
<img src='images/media-button-video.gif' alt='$video_title' />
<img src='images/media-button-music.gif' alt='$audio_title' />
<img src='images/media-button-other.gif' alt='$media_title' />
EOF;`
it just removes onclick="return false;" which i found not useful.