If you get the above error when installing TFS 2013 Update 4. You may find the following article useful.

http://blogs.msdn.com/b/heaths/archive/2014/05/23/update-does-not-apply-or-is-blocked-by-another-condition-on-your-computer.aspx

In my case I installed another program that required Update 4. In this case because it was a test machine I installed Visual Studio 2013 and Update 4 suddenly worked.