>How would I code:
>
>If myprog.exe is running
> Don't run it again
>Endif

Here is what I use for it:

* At the beginning of your Main Prg
IF IsRunning(SomeUniqueForApplicationString)
   MessageBox("Application is already running")
   QUIT
ENDIF



FUNCTION IsRunning(tcSemaphoreName)
    LOCAL lpszSemName
    #Define ERROR_ALREADY_EXISTS 183
    Declare Integer GetLastError In win32API
    Declare Integer CreateSemaphore In WIN32API ;
            string @ lpSemaphoreAttributes, ;
            LONG lInitialCount, ;
            LONG lMaximumCount, ;
            string @ lpName

    app_href = CreateSemaphore(0,0,1,tcSemaphoreName)
RETURN (app_href # 0 .AND. GetLastError() == ERROR_ALREADY_EXISTS)

The original code of that function is made by Cetin (I think), at least I get it from his post here.