It seems, there is a major problem with the Server CU.

Critical Information about a problem with the October 2010 CU for SharePoint Server 2010

SharePoint 2010 October Cumulative Update Issue: Details and Workaround

Packages Impacted

The Cumulative Update packages affected are the Server Packages for SharePoint Foundation, SharePoint Server and Project Server 2010, specifically;

1. SharePoint Server Package 2394320
2. Project Server Package 2394322

The downloads for both of these packages have been removed from our servers.  If you have already downloaded them you SHOULD NOT install them.  They will be republished.

Update 18.11.2010

An update, which addresses the issue, has been released: http://blogs.technet.com/b/stefan_gossner/archive/2010/11/18/october-cu-for-sharepoint-2010-has-been-rereleased.aspx