I used several builds-rc's-and also the very latest version (zdesktop_1_0_build_1593_win32.exe) on different systems (different computers or re-installed windows), and also 15++ reinstalls (clean, dirty, semiclean, while running, eating, sleeping). My first attempt was 4 months ago.
So I assume I don't need to reinstall or do something similar (pls dont tell anything like that, I will not).
127.0.0.1 thing is ok.
Yahoo! Zimbra Desktop Service seems to working.
I saw many (many) user-candicates have exact same problem.
I add log files.
same problem (exact same I think)