I have a similar problem, in that I can disable the Connect Automatically option ONLY for networks that I have connected to. All other (i.e. neighbouring) networks have the Connect Automatically option turned on, and I CANNOT change this - if I turn them
off, they just come back on again the next time I check.
The reason this is a problem for me is that I've had another bug that's related to this. Every time I woke upmy computer (I put it to sleep rather than shut it down) it would take awhile before I could connect to the internet, even though I was connected
to my modem/router via a wired Ethernet connection. I traced it to my computer trying to connect to several wireless LANs automatically, even though there's a wired connection and even though it never ultimately connected to any of the WLANs. It seems that
while it is trying to connect to a wireless LAN, it cannot connect to the internet over Ethernet. I disabled Connect Automatically for all my own wireless LAN networks, and succeeded, and tried to do so for all other nearby wireless networks, and failed.
The problem has largely gone but comes back every so often.
I have an HP Pavilion p6755a PC with a Ralink wireless LAN card using driver version 5.0.37.0 by Ralink Technology Corp. The ethernet card is a RealTek PCIe GBE Family Controller with driver version 8.2.612.2012 by Realtek.
UPDATE: Just tried to update the Ethernet driver and it 'updated' the driver to 8.1.510.2013 by Microsoft. The 8.2.612.2012 version came from HP's support site where it's still listed. The wireless LAN card driver doesn't have an update.