Hello Jerry, if the problem were this, I could do login with a SQL Server user, but I get the same error with both kind of users...

In the begining I thought that that was the problem. But in the event viewer is not a error of that kind :-/

I have just install the SP4, but still having the same problem...

I'm going to install a fix...

http://support.microsoft.com/?kbid=891311