I fixed my login looping problem just by editing the session in the preferences under the admin control panel. it all works fine now. I went into the preferences, checked to use custom sessions then just edited my session time to lik 180mins or so since I stay logged on for long periods of time in the bg. works fine for me.

y tried the sites listed above and y have no problems at all, its kinda funny, y hosted my site (http://www.viciopolis.tk) on a apple 800mhz 256ram trough a 512 kb connection, and some users, some times, not always get stuck in the login loop, i tried everything in the list, take off firewall, increase the session time, and not to use other software, but i still have two issues,
1.- The login loop, people keep telling me that when they have problems login in at www. they try my ip adress and everithing work fine (strangely just 1 or 2 times it didnt worked too) and.... people from a isp cant post... long post, they can post short post, but, large ones or post with pictures they cant...
any ideas..