as I said, it looks like bugs in Mono, only the Mono team can fix it, it is not a configuration issue.
If you want a stable installation of mojoPortal I recommend use Windows hosting, almost every version of Mono they fix some bugs but they introduce new ones, very rarely you may get lucky with a Mono release.
I wish Mono was a stable platform for ASP.NET, but as long as the Mono web site runs on PHP and Novell does not run any important web sites on ASP.NET/Mono I don't think it will ever happen. I've been waiting since 2004 and it is very much the same today as back then. Not enough testing of Mono is done with complex ASP.NET web applications and there are almost always problems in each release of Mono.