In the example below, you can see that Umbraco is installed in a virtual directory called "umbraco" which is a child of the Default Web Site. This will cause the standard paths to be incorrect. This installation was done with Microsoft's Web Platform Installer, which does not appear to correct for the problem.

Here is a copy of the appsettings portion of web.config file (located inside the umbraco folder) with the paths corrected for the folder configuration shown above. Just open it up and edit it with notepad to fix.

<appSettings> 
<add key="umbracoDbDSN" value="datalayer=SqlServer;server=server;database=db;user id=dbuser;password=password" /> 
<add key="umbracoConfigurationStatus" /> 
<add key="umbracoReservedUrls" value="/umbraco/config/splashes/booting.aspx,/umbraco/install/default.aspx,/umbraco/config/splashes/noNodes.aspx" /> 
<add key="umbracoReservedPaths" value="/umbraco/umbraco/,/umbraco/install/" /> 
<add key="umbracoContentXML" value="/umbraco/data/umbraco.config" /> 
<add key="umbracoStorageDirectory" value="/umbraco/data" /> 
<add key="umbracoPath" value="/umbraco/umbraco" /> 
<add key="umbracoEnableStat" value="false" /> 
<add key="umbracoHideTopLevelNodeFromPath" value="true" /> 
<add key="umbracoEditXhtmlMode" value="true" /> 
<add key="umbracoUseDirectoryUrls" value="false" /> 
<add key="umbracoDebugMode" value="true" /> 
<add key="umbracoTimeOutInMinutes" value="20" /> 
<add key="umbracoVersionCheckPeriod" value="7" /> 
<add key="umbracoDisableXsltExtensions" value="true" /> 
<add key="umbracoDefaultUILanguage" value="en" /> 
<add key="umbracoProfileUrl" value="profiler" /> 
<add key="umbracoUseSSL" value="false" /> 
<add key="umbracoUseMediumTrust" value="false" /> 
</appSettings>