Couchbase Console error

Couchbase Console login works for some time and it stops working any more. Certain times getting this error message:

http://localhost:8091/
Getting the following error:
This site can’t be reached
localhost refused to connect.
Search Google for localhost 8091
ERR_CONNECTION_REFUSED”

other times accepts the password and do nothing. Tried on both IE and Chrome. Host machine is Windows 7; Couchbase Version 4.6?