This is Windows 7 SP1 I trust and fully updated?
Not sure if I have a solution as I read your other thread and I hate to say but if it were my machine I would format and reinstall the system. Have you been using registry cleaners? I ask because your problems sound very like those of others who have. They are basically system destroyers, believe me.
It could be !
I assume that right-clicking the Network icon by the clock and selecting Diagnose and Repair doesn't fix it.
that's correct.
I experienced a problem with the Network Icon and the yellow exclamation mark a couple of months ago, it wouldn't go away and then I managed to cure it by disabling network adapters I wasn't using in Device Manager. I had forgotten that I'd updated several drivers, which reactivated unused stuff. Each system is different in this regard, mine has 2 built-in Network Adapters for starters, so disabled the one I never use. Plus there was 1 wireless one that I never used and a Bluetooth one, also that I never used, so once those were disabled and few reboots later to get the system to 'settle in', the icon network connected first time, each time.
I will try system format.
You might also want to check, if applicable, your security protection software and see if it has an issue with network protection.
I turned off all firewall
I'm afraid that's all I can suggest. Maybe someone else has ideas, hopefully.