The AssetUrlSelector class, and the Asset Picker dialog box returns an absolute URL in Microsoft SharePoint Server 2010. However, users expect to receive a relative URL.
To resolve this issue, install the following update rollup:
2534412 Description of the SharePoint Foundation 2010 hotfix package (osrchwfe-x-none.msp): April 21, 2011
After you apply this hotfix package, the default behavior of SharePoint Server 2010 changes. SharePoint Server 2010 now returns a relative URL instead of an absolute URL. Additionally, if a selected link is in a different web application, SharePoint Server 2010 still returns an absolute URL. However, if you want to restore the previous behavior of SharePoint Server 2010, set the returnAbsoluteUrl property of AssetPicker configuration element under the SharePoint section to True.
Note The following code shows this section that is located in the web.config file.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<section name="AssetPicker" type="System.Configuration.SingleTagSectionHandler, System, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<AssetPicker returnAbsoluteUrl="true" />
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.