Ok - so have changed tnsnames so that it looks like

xe =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.162)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = xe)
(INSTANCE_NAME = xe)
(GLOBAL_NAME = xe)
)
)

but still no joy! Have tried connecting and still get the same error as detailed above (this is after restarting the db by the way).