Column Name Disappearing from Candidate List

I have a table with a column called 'PlannedStaff'. When I type 'select pla' into the Management Studio editor, the candidate list displays the PlannedStaff column and the PLAN keyword in the All common objects list. If I then type 'n', the column name disappears, leaving just PLAN in the list. Switching to the Columns from all tables list correctly displays the PlannedStaff column.

I am using Management Studio against a SQL Server 2000 server.