What OS? If on a Mac, then check the shortcuts being used by Spotlight.
Does the same thing happen on a new document? If yes, I would close ID and restart.
If that doesn't work, I would try re-starting the workstation, If that doesn't work, reset your Preferences...
(Leave reset prefs to last option unless you have a backup of them)
Win - Start InDesign, immediately press Shift+Ctrl+Alt. Click Yes to delete preference files
Mac - Start InDesign, immediately press Shift+Option+Command+Control, Click Yes to delete preference files
More info is available here:
Deleting the prefs will not help with this in most cases. It's a known issue in Mavericks that the OS steals these shortcuts.
Go to System Preferences > Keyboard > Shortcuts to look for the conflicting OS option, and change its shortcut
Thank you for the suggestions!
Larry, I am using a Mac, running 10.9.2
Sue, I have previously trashed the preferences to no avail, Peter seems to be correct.
Steve, that seems to have taken care of the problem! Although I didn't notice any conflicting shortcuts, I tried restoring the defaults for kicks and the problem seems resolved.