I just re-installed SharePoint Server 2010 and Central Administration kept giving me a 500 IIS error:
"Could not load all ISAPI filters for site 'SHAREPOINT CENTRAL ADMINISTRATION V4'. Therefore site startup aborted."
"Event ID: 2268"
The reason is that I had previously installed Forefront Security for SharePoint on the same box, and after I uninstalled SharePoint 2010 Forefront was "orphaned" you could say. After I uninstalled Forefront, the 500 error went away.
Phil