Welcome to TSF :wave:
Are you sure its "downloadhost.exe" ? Nothing found in Google so I am assuming it is some type of malware.
The security team can help you with this.. You are probably infected. We cannot assist you with this issue here in the Microsoft Support Forum.
Look over these
http://www.techsupportforum.com/sec...read-before-posting-malware-removal-help.html
If you cannot complete any of the steps for whatever reason, just continue on with the next one until they are all completed, and post your logs in
Virus/Trojan/Spyware Help; where an Analyst will assist you. However, it is very important to make mention of any of the steps that you were not able to complete.
After you’ve posted your logs, please be patient, as the Security Team Analysts are very busy.