Try d/l ing and running the Malicious software removal tool, do a full system scan and see what it finds. Also try d/l ing Malwarebytes and do a full system scan. Once you update Malwarebytes, do the scans disconnected from the net.
If you have problems running those, then your system may be seriously compromised by a virus or malware. Post back & let us know the results. Initial Google searches point to a possible infection.
Also, you may wish to consider d/l ing and re-installing MS Security essentials. Download details: Microsoft® Windows® Malicious Software Removal Tool (KB890830) x64 http://www.microsoft.com/security_essentials/ Malwarebytes Troj/Mdrop-DHC Trojan - Sophos security analysis
Edit: I found this on a Malwarebytes log online:
c:\program files\common files\microsoft shared\web components\messenger.exe (Malware.Gen) -> Quarantined and deleted successfully.
If it's the same thing you're seeing, Malwarebytes should be able to delete it.