Number Keys don't work consistently in Latitude E5520

The HOME and END keys on the number pad area of my keyboard don't work consistently on my Dell Latitude E5520 when I'm using them NOT as numbers but as directional keys.  They work as they should in Lotus Notes, Outlook, Notepad, Windows Explorer and in some other software applications but they do not work correctly in forms in web browsers.  For example in while I'm writing this post when I hit the HOME key intending to move to the beginning of the current line I instead get the number 7 written at the cursor point.

This problem began when I reinstalled Windows 7 a second time on my laptop.  I believe I installed all the Dell drivers for my laptop correctly and even tried reinstalling the ALPS Keyboard Touchpad driver but it still won't work correctly.  I recently upgraded to Windows 10 and the behavior is exactly the same.

Thanks very much!