Is your OS pirated??? If it is then don't download anything from the microsoft website and just format your entire PC coz you are accepting virus programs from the site... Thats the only solution...
If you don't know whether your OS is pirated, try downloading files from other websites... If there's no such problem, your OS is pirated... Format your PC... If your OS isn't pirated then there might be some problem with your DLL files... Reinstall your OS... Finally, this will help...