So, I've been on HB all day on two different machines. I updated one and had the settings error and deleted the "kiting.cs" file to resolve the issue. I updated on my laptop via downloading 2.5.6485.511.zip since my internet crashed while the downloader was running. Once I did it that way, I was getting the same Authentication errors as others (even though I can log in via the other machine just fine). So I downgraded to 2.5.6396.497.zip and I can log in just fine. I went through the autoupdater and not I am using 2.5.6485.511 as noted in HB and can log in just fine. I am doubting that it is a firewall/DNS/etc. issue as has been advised. Perhaps there is something wrong with the 2.5.6485.511.zip package.
It's open. 511 when using autoupdater works...511 when downloading the .zip and doing a fresh install, does not work. Also, at the same time, 511 via autoupdater on PC1 works but 511 via fresh install on PC2 doesn't work. When I use an older version on PC2 then upgrade to 511 via autoupdater it works. No changes on any PC/router/etc. Are you saying that 511 via fresh install uses port 80 (which is open on everything I can control...ISP may block for some dumb ass reason to keep me from hosting a website at home, maybe) but 511 via autoupdater uses another port?
try this Hb build (507) Home and if you still have problems open new thread including your log as attachment