So that's what it was about - thanks for explaining it so clearly. I can confirm this bug (FMA 10.0v1, OS X 10.5.6).
If I remember my "bug threads" correctly, this is a known bug and it also applies to fields with conditional formatting as well as buttons. In otherwords, a field referenced in the conditional format expression of any object is added to the table.
Any workarounds that you have found
A further investigation reveals more about the nature of this issue, and also how to solve it:
In version 10, there is a new way to control which fields appear in table view. It's called 'Modify Table View' and it's available instead of 'Edit Layout' when you are in Table view. In this window, you can set any field to show or hide - whether it is on the layout or not:
What actually happens here is that the field referenced in the conditional formatting formula gets automatically turned ON to show in Table view. And the solution is simple: click the 'Modify' button and turn it OFF.
Yes, this is a known problem. It was first reported on this forum back in April.
Please read the thread as there are other consequences to this issue; namely Merge Fields. As stated in that thread, our Development and Software Quality Assurance (Testing) departments are aware of this issue.
KoenVanHulle - Thanks for the detailed post. Very straight-forward and to the point. Excellent.