Enter Key and Tab Key stopped working in Win 7 x64

Yesterday, both keys failed. But not a HW problem:
1. They work fine in Linux and in Lenovo Test environment.
2. The on-screen Windows virtual keyboard fails in the same way.

I used a key sequence suggested in Keyboard - Key not working? which seems to have helped problem, but not solved it.

Now, in Notepad, I can used Ctrl-Enter to create a New Line action, but this doesn't work universally. For example, when writing an email in Firefox->Gmail.
(Also, I am writing this report in Notepad and will paste it into the forum since keys don't work here.)

Also in Notepad, ctrl-Tab does a tab action.

About the time it failed (+/- a day because I don't know the exact time of failure) I installed:
QuickBooks Pro 2009
Google Desktop
SupportSoft Assisted Service
Adobe Air

I am puzzled. I will try anything you think may help.

Have you tried System Restore General Troubleshooting to Fix Issues

You can also try SFC /SCANNOW Command - System File Checker

Quickdraw

Thanks for the pointer to the list of things to try. One of them worked; I don't know which one.
Phil

Happy Computing!

Quickdraw

SOLVED