How exactly are you running mserver5.exe? Are you running the batch file
C:\Program Files\MonetDB\MonetDB5\M5server.bat (assuming that you used the
default installation paths), are you running
C:\Program Files\MonetDB\MonetDB5\bin\mserver5.exe with your own arguments,

or are you starting the server by clicking Start --> MonetDB5 --> MonetDB SQL Server?