We run into this frequently. What version are you at? Up until R13, we recieved it frequently in Section View, usually with parts that contained surfaces imported from another package. The only fix we found was to move the section slightly.
At R13, the section view Red X problem went away, but we are now seeing it occasionally on Projection Views. Usually running a CATDUA on all of the parts fixes it.
Are you running with VPM? If so, another thing that may cause the Red X prolem is parts with Slashes in their Part Name (not Part Number, but Part Name). Somehow, R13 doesn't like this very well. I can't verify this yet, but it is something to look for.