I have this problem and found this really annoying too.
Opera 18.0
Mac OS X 10.9.1
Almost everytime, when I hit the enter key in the address bar.
Sometimes it will,
- bring me to google search even I enter a URL
- show no response, empty page when I enter a URL, or a search token ( I need to go back to the address bar and enter key couple more times to get it work. )
- When I enter search token, it only search part of my token. ( I needed to wait for like 2-3 sec to get it display the dropdown list in order get it runs correctly. Maybe it's better to start giving me search suggestion if I stop entering for like 2-3 second. For speedy search token entered, I DON'T need suggestion since I know what I need to search...)
PS: This is the first time I use Opera.