hey guys am having the same exact issues..here is what is in my error log..
[Thu Jun 11 16:25:03 2009] [error] [client 97.215.118.204] (13)Permission denied: file permissions deny server access: /home/folder/public_html/wp-content/themes/bphome/style.css, referer: http://site.com/wp-admin/themes.php
[Thu Jun 11 16:25:01 2009] [error] [client 97.215.118.204] SoftException in Application.cpp:252: File “/home/folder/public_html/wp-admin/themes.php” is writeable by group, referer: http://site.com/wp-admin/wpmu-themes.php
[Thu Jun 11 16:24:48 2009] [error] [client 97.215.118.204] (13)Permission denied: file permissions deny server access: /home/folder/public_html/wp-content/themes/bphome/style.css, referer: http://site.com/wp-admin/themes.php
what permissions should i set ? coz i cant even see the thumnail for the theme