If you're like me then you will use the keyboard for a lot of things that every day users use the mouse for. Also for going back a field, rather than cycling through the entire form/window using the Tab butting you will use Shift and Tab Key. However for some strange reason it stopped working on all my vista machines. Initially I thought it was a profile issue, so I deleted the locally stored profile, renamed the network profile logged on and let it re-create, but no that did not fix it.
I then installed a new PC with Vista and the Shift and Tab worked, I then installed Office 2007, it still worked, then ran Windows Update, still worked. Installed a load of stuff and it still worked. I scratched my head a bit more and wondered what could be causing it. I then installed Windows Live...
... Live Writer fine, Live Messenger, fine. Live Toolbar, and I had the problem!
So I then uninstalled Windows Live Toolbar off the PC's affected and shift and tab worked straight away.