levo - 5:07 pm on Jul 27, 2012 (gmt 0)
CNAME causes double DNS lookups. Check your non-www record, it should have an A record with your servers IP address. You can delete the CNAME for www and create an A record with that IP address. To be on the safe side, contact your hosting provider. BTW, it might have nothing to do with the site health, but by any chance WMT sorts them based on response time, that might explain it.