For some reason (all of a sudden), I'm no longer able to toggle the toolbar Reference button -- even when I have an active reference file (wav) loaded.  The button is now grayed out --  just won't work.  I've never had a problem with this before.
I noticed this problem a day or so after uninstalling and reinstalling some totally unrelated software -- Adobe Acrobat Reader.  I'm not sure how this would affect the function of the Reference button, but I suppose anything's possible. 
Any thoughts?
Tom