Hi,  Found the sollution in the meantime. OMClean did the trick.
I get the following message when trying to install OpenManage 5.2.0: An older version of Server Administrator or Management Station software is detected on this system. You must uninstall all previous versions of these applications before installing this version.  I can't uninstall an older version, as there is no older version installed. No Dell software is listed in the Add/Remove software dialog. Any ideas? I guess some registry key is incorrect.   Kind regardssteven
Failure installing OpenManage 5.2.0 on PE2850