In your corridor properties, are all you baselines turned on?
I'll go and uncheck my baselines to speed up my drawing, and it never fails - I always wonder what happened to my corridor surface, my surface profiles disappear from my sections/profiles, etc. Then I remember to create a detached surface!
A couple of other things to check is:
1) Did you actually add top links to the corridor surface you created?
2) Layers frozen/thawed?
-Bruce