There is definately some weird behavior of IE (6.0SP2)...
Firefox:
1. Click Login link
2. Enter credentials
3. Login done
HFS log:15.08.2006 00:47:19 192.168.1.100:2656 Connected
15.08.2006 00:47:19 192.168.1.100:2656 Got 514 bytes
15.08.2006 00:47:19 administrator@192.168.1.100:2656 Sent 94 bytes
15.08.2006 00:47:19 administrator@192.168.1.100:2656 Requested GET /~login
15.08.2006 00:47:19 administrator@192.168.1.100:2656 Request dump
> GET /~login HTTP/1.1
> Host: pluto:81
> User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6
> Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
> Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
> Accept-Encoding: gzip,deflate
> Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
> Keep-Alive: 300
> Connection: keep-alive
> Referer: http://pluto:81/
> Authorization: Basic <authenticating string>==
15.08.2006 00:47:19 administrator@192.168.1.100:2656 Redirected to /
15.08.2006 00:47:19 administrator@192.168.1.100:2656 Disconnected by server - 94 bytes sent
15.08.2006 00:47:20 192.168.1.100:2657 Connected
15.08.2006 00:47:20 192.168.1.100:2657 Got 508 bytes
15.08.2006 00:47:20 administrator@192.168.1.100:2657 Sent 1148 bytes
15.08.2006 00:47:20 administrator@192.168.1.100:2657 Requested GET /
15.08.2006 00:47:20 administrator@192.168.1.100:2657 Request dump
> GET / HTTP/1.1
> Host: pluto:81
> User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6
> Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
> Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
> Accept-Encoding: gzip,deflate
> Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
> Keep-Alive: 300
> Connection: keep-alive
> Referer: http://pluto:81/
> Authorization: Basic <authenticating string>==
15.08.2006 00:47:20 administrator@192.168.1.100:2657 Served 1,12 KB