After I ugraded to the latest version of the blog module, the formatting got screwd up. It does not look anything like the formating on this page:
http://www.dotnetnuke.com/tabid/825/default.aspx

Both the dotted and solid horizontal ruler is missing together with different font type and size. Anyone know what could be the problem? One of the first time I logged in after upgading it was OK, but after that it has been wrong.

The following is in the top of the html page:

<link id="_DesktopModules_Blog" rel="stylesheet" type="text/css" href="/DesktopModules/Blog/module.css" />

When I check this file it only contains the following:

 /* ================================
    CSS STYLES FOR Module Blog
   ================================
*/
.BlogInfo
{

}

.SearchOptions LABEL
{
 font-family: Tahoma, Arial, Helvetica, Serif;
 font-size:x-small;
 
}

.CreateFrom
{

 font-size: 10px;
 color: #003366;
 font-family: Tahoma, Arial, Helvetica, Serif;
}

(The site is online, but it is password protected, and I dont want to post a usernam/password on this forum.)

Ole Jørgen Legård wrote Could it be some caching issues with my service provider?

Sounds as if that could be the case.  Also try making sure IE's cache is clear.