I wanted to post this in case anyone else was having the same problem.  Sorry if it's already been posted.
 
I love the nudge feature and especially love to use my number keypad to the right of my QWERTY keyboard for the shortcut keys (e.g., number 1 nudges a selected clip to the left once, number 4 nudges a selected clip to the left twice, etc.).  But sometimes the shortcut keys wouldn't work and I could never figure out why until now.  Sometimes, instead of nudging the clip, the shortcut keys would make the track view jump to somewhere else so that I could no longer even see the selected clip I was trying to nudge.
 
It turns out that the key (no pun intended) is the "0", or "Ins" key on the number keypad (not to be confused with the "Insert" key, usually located further up and to the left). 
 
It's easy to accidentally hit the "0" key with your right thumb since it's usually located at the bottom of the keypad where your right hand would be using the keypad.  When this happens it renders the shortkey keys for the nudge feature inactive until you hit the "0" key again.
 
Cheers!

Thanks for that. I've noticed a couple of weird things happening with Nudge, so maybe this is the solution.

You're welcome, Jonesey.  Hope that works for you.
 
Cheers,
 
    Terry

I should also mention that the "Num Lock" key on the numeric keypad also has to be depressed for the nudge shortcut keys to work.  I already knew about that key though.  The "0" was overriding the Num Lock key in my case.

SolidTerry - thank you so much - I've been driven crazy by this.
 
Re-entering the stress free zone!
 
Cheers friend!
 
Gary 

Wow! Great information. That solves a problem that had me really steamed. Lots of smart people here.
 

You're welcome Gary and Dana.  Glad I could help.