I found the code below on how to check for a previous instance of an app, but I don't think this will work for a network executeable. So, how do you check to see if there is multiple instances of an executeable running on a network?
Public Sub CheckForExistingInstance()
'Get number of processes of you program
If Process.GetProcessesByName _
(Process.GetCurrentProcess.ProcessName).Length > 1 Then
("Another Instance of this process is already running", _
"Multiple Instances Forbidden", _