I have the same problem as well.
Seems like a trojan hidden in one of the Chrome extension. Just don't know which one.
I have found this webpage on the same topic: http://www.eenyhelp.com/answer/bug-811371-chromium-unwanted-redirection-chromium-help-215926861.html
Quick and dirty way to block it: block access to www.free-merchants.com (either on the router or at least in hosts file on the local PC)
Proper way: find the guilty extension and disable it.