i'm also having this problem , i have read all through this thread and didnt find an answer. . .
zimbraAdmin dosnt open in firefox (ver 188.8.131.52) - just a gray page.
zimbraAdmin dosnt open in IE 7 - just a grey page.
(there is an icon showing there were errors loading the page...
... error: 'ZaZimbraAdmin' is undefined
. . . . )
also tryed maxthon and a few others - none worked.
all from the same computer.
from another location it works fine.
and from the problematic computer i can still get to the normal (not https) webmail page.
(please dont ask me if i've put in "https://" in front of the address, we are way past that stage... )