At a company I work for we recently had to downgrade from the 64 bit version of Microsoft SQL Server 2005 back to the 32 bit version (long story :) ). After removing the 64 bit version of SQL Server and installing the 32 bit version and then recreating the master db and setting up all of the databases again, Optimum no longer worked correctly. I could log in fine, but whenever I tried to open up Employees, or just about anything else, I got a big nasty error message saying “you must declare the scalar variable @USERID”. Read on for the solution to the problem.