I usually avoid sequence structures in favor of driving execution order through data dependency (error clusters are great for that). However, since you've already got one, you coul try to add another frame right before your event structure. In that frame, place another event structure that can trap that stray keyboard event. Put a tiny timeout value on it so it doesn't appear to "pause" your VI's response. That event structure will catch any bogus key presses that happen during initialization.
Having said all that, I still think the behavior is not proper. The event should not be handled if it happened before your VI gets to the event structure. For now, you can try that workaround.
Daniel L. Press
PrimeTest Corp.
www.primetest.com