Hi,
The main problem seems to be that the extensionless urls are not working, IIS is returning a 404 page not found for those urls without passing the request to asp.net so mojoportal code is not even handling the request and you see the IIS 404 page.
If you don't have IIS 7 or higher, extensionless urls are not going to work. I suggest read the article about Extensionless Urls and check all configurations mentioned there, ask your host about the IIS version and if it is not 7 (which has been out since Windows 2008) or higher I would recommend looking for different hosting. I would not use any hosting that puts your site on some old legacy Windows 2003 machine.
Hope that helps,
Joe