one pc on network and one off

Hello Win 7,i5,650GB, Win 7 , MSIE9.

Because the desktop had internet but the laptop did not, I ran an MSE scan then MBAM in safe mode with networking but networking did not function.
I still had no internet in the laptop and nothing was detected.

I restored the registry to yesterday with tweaks program as system restore has failed me before and they now both have internet.

My wife said she saw something in the lower right corner of the systray and cannot remember whether she clicked on it to install or it just did it automatically. She cannot remember what it was. I have Windows set to ask me before installing. I think I will change that to ask me before downoading or installing.

I have MSIE 9 default to desktop but she was not online.

Is there somewhere I can look to find out what it was?

What would have caused the laptop to lose internet that restoring the registry to yesterday would have fixed?

Thank you

Hello
I knew about the key and in my haste neglected to check it.

I have made your link a favorite and have read it.
I did know some of it but it really helps to fill in the parts I did not. Thank you very much.
Peter