It appears that when I make a schema change in a table from SQL Management Studio (right click table--> design) that the record in ST.GEOMETRY_COLUMNS gets removes along with the associated table functions.
At this point spatial queries using the table functions fail. However, the geometry column is left in the table along with the triggers, etc, however the envelope columns remain. At this point the system is in an inconsistent enough state the st.addgeometrycolumn and st.dropgeometrycolumn fail and the only solution I have found is to manually remove all of the SQL Spatial objects from the table manually and then run st.addgeometrycolumn again.
At this point spatial queries using the table functions fail. However, the geometry column is left in the table along with the triggers, etc, however the envelope columns remain. At this point the system is in an inconsistent enough state the st.addgeometrycolumn and st.dropgeometrycolumn fail and the only solution I have found is to manually remove all of the SQL Spatial objects from the table manually and then run st.addgeometrycolumn again.