This problem happens especially in the latest versions of DotNetNuke (7.0 or later). It is shortly represented like this: when you install DotNetNuke and everything appearance fine. You log in to your system using your host account and so your homepage keeps refreshing indefinitely. you'll not get rid of that “Getting Started” pop-up. after you manually instert the url of different pages in your web browser url bar (like, you get a 404 not found error.

To solve this problem, apply the steps below:
1. Find the folder within which your DotNetNuke web site is installed and find your web.config file there and open it (normally, i open it with a development application like Visual Studio or notepad++ for better undestanding however classic Notepad can do fine, too).

2. On the web.config file, you should find the <system.webserver> tag.

3. On this tag, find <modules> tag. And update this tag:
<modules runAllManagedModulesForAllRequests=”true”>

4. Then, Save your web.config file. Close your browser, open it again and open your website. Log in with your host or admin account. You will see that the problem is fixed.

Obviously there may be different components which cause this issue yet i have made bunches of DNN establishments and i've generally figured out how to settle this issue by applying the steps above.

Note: If you have done all the steps and still get a 404 error, than check your default documents in IIS and see if there is default.aspx in there. If not, add it.