Keyboard Shortcuts not working in Word

After some kids where playing with my laptop, some of the keyboard shortcuts stopped working in Word 2007. Actually it's Ctr+Z, Ctrl+A, Ctrl+S, Ctrl+X, Ctrl+C and Ctrl+V. Although the alternative combination for "select all" still works "Ctrl+Num5".

Although, at the same time, all shortcuts are working properly in Excel or Powerpoint.

I tried reseting the custom shortcuts but the button is greyed out, so there must have not been made any changes there.
Then I copied fresh all the templates (norma.dot, normal.dotm etc.)
The last thing was to uninstall Office completely, follow the steps for manual uninstall and deleted all files/registry keys relevant to office and reinstalled but still the problem remains.

Any suggestions plz?