This seems to happen pretty regularly. I start manually populating columns for an INSERT Statement because I don't want to insert data for all columns. I start getting a drop-down of available columns when I start typing a column name, but when I try to auto-complete a column, I get an exception.
Running latest SQL Prompt v4 beta, SQL 2008 SP1 tools, against SQL 2005 server.
Running latest SQL Prompt v4 beta, SQL 2008 SP1 tools, against SQL 2005 server.