I use the twenty ten theme. (as a child). This problem also occurs with the parent 20-10 activated and have tested also with twenty eleven. The issue occurs on three different accounts with 2 diff hosts.
2 days ago when customizing a new draft site (on a sub-domain), I noticed on 1 account with "Host A", that when setting the site-theme up with the the theme's wp admin customize link, the sample preview page continually reloaded (In the admin). I uninstalled and reinstalled WP (as this was a new setup) and things initially seemed fine.
Today - same problem is back again. I thought it might be an issue with the host. The issue was happening on another account I have with the same "Host A" as well until investigating further; I checked on a site I have with another "Host B" and the same problem exists there as well.
In admin the url is: the-sites-domsin.com/wp-admin/customize.php
Can anyone help direct me on possible causes or trouble shooting of this? Thank you in advance.