I finally figured it out... it was the Bing Bar. I must've inadvertently downloaded and installed it the day I worked from home and grabbed the Windows Live Essentials 2011 pack.
Went thru a process of elimination - uninstalling all Win Live programs with a date of 1/10/11 or something like that; and voila - my keybind now works regardless if I'm tabbing out.
Such a pain. Thanks, Windows. t('.'t )
