Are you posting from the affected computer as I was wondering if your Internet connection is affected.
If you do have an Internet connection then I would advise booting up into Safe Mode with Networking and running a scan with ESET Free Online Scanner.
http://www.eset.co.uk/Antivirus-Utilities/Online-ScannerClick on Advanced and check all boxes except the Proxy one then disable your AV program immediately before hitting the Scan button.
Your AV program should be isolated in Safe Mode with Networking but aspects can still be loaded.
If you aren't able to download any programs then go Start - type
mrt.exe - press enter and opt for the full scan.
Following that if you are still unable to download, see if you can open a command prompt as an administrator and enter
sfc /scannow to see what that reports.
If WR doesn't do it then this Batch file may help
http://batcmd.com/windows/7/services/dcomlaunch/Getting the DCOM started to enable RPC will probably resolve the other errors, but check Event Viewer to see if MS has any solutions by clicking on the blue Online help link.