I'm not sure what kind of error could occur in that
case, that's why error logging might help. I doubt it because the original
callback is being made, but it doesn't hurt to try it.
I've never seen a case in either Outlook 2007 or
2010 where what you are describing happens. Usually if a callback works
initially it will work when forced by either of the ribbon invalidation methods.
Are you sure you're actually hitting the code line
or lines that are invalidating the controls?
Where are you calling to invalidate the controls?
What event handler or other place in the code?