I once encountered this error on a Win 2003 server and rebooting solved it. I think I also made sure it had all the windows updates and then rebooted again.
I do not believe this is an error in mojoportal code, it is a known issue in ASP.NET and there is a hotfix that can be applied if a couple of reboots does not solve it.
Related links:
http://stackoverflow.com/questions/1826718/system-drawing-gdi-is-not-properly-initialized-internal-gdi-error
http://blogs.msdn.com/vijaysk/archive/2008/09/02/using-themes-in-asp-net-loads-system-drawing-namespace.aspx
http://support.microsoft.com/kb/975410
Hope it helps,
Joe