I get an error dialog telling me that VBS2Combined Arms is already running when I start

VBS2Combined Arms will check that there is not another version of VBS2Combined Arms running which is using the same ports that it requires for operation. If there is another version running, it will display an error message and will not start a second version on the same computer. Close the first version down.
Use windows task manager to close all java processes and then run VBS2Combined Arms again.