In a previous thread I read that the guest account must be inactive. It is but it dosen't work anyway.

I have the same problem. My PC runs Windows XP, .NET 1.0, 1.1 and 2.0 versions and SQL Server 2005. After plain install of episerver 4.61 I cannot login. Checking IIS settings I found that episerver ran as ASP.NET 2.0, so I changed that back to 1.1 and that did not help either. Next I installed hotfix 5. That one updates a stored procedure that returns the episerver tabase version; was 96 became 98. I suppose 97 was another hotfix. Did all other things required by the hotfix. Still no login. Next I installed ASP.NET 2.0 templates, changed ASP.NET back to 2.0 in IIS. No luck. Next, I removed episerver virtual directory from IIS. Open web project in VS2005 and try debugging through VS2005 internal web. No I get intermittend complaints about expected database version 96 not being equal to 98. Seems that hotfix 5 is incomplete. Next, changed web.config to use windows authentication. Now the site does start up and does the initial content load. Next, change back to forms authentication. Try login by clicking on the key and enter admin name and password. Now I am logged in as pc\\guest (my machine name is pc). Any ideas?

I've bumped into simmilar problems many times and re-installation has been the key, sometimes over and over again. However last time I had time left over to investigate and started SQL Profiler to see what was actually passed on from the login-screen. I wasn't suprised to see that the username / pass i entered in the form wasn't passed on at all, instead it sent localpc\Guest. For some reason EPiServer sometimes use windows authentication even though Forms is to be used. My solution is changing in the web.config to disable windows authentication and only use forms. Might not be an option if you really need windows authentication. Here goes. In add a security config section. Looks like this in my config:

in the add these lines That will enforce database only authentication and also use caching. Hope this works for you as it does for me. If not, try spying on episerver stored-procedure calls with SQL Profiler and see if that gives any clues.