我编的软件生成EXE时候 为什么可以一直打开？我打开了一个，在点击这个EXE文件的时候还能打开，有什么办法可以解决吗？

可在你程序加入模快：
Option Explicit

Private Const ERROR_ALREADY_EXISTS = 183&

Private Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type

Private Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" (lpMutexAttributes As SECURITY_ATTRIBUTES, ByVal bInitialOwner As Long, ByVal lpName As String) As Long

Private Sub Main()
Dim sa As SECURITY_ATTRIBUTES
sa.bInheritHandle = 1
sa.lpSecurityDescriptor = 0
sa.nLength = Len(sa)
Call CreateMutex(sa, 1, App.Title)
If (Err.LastDllError = ERROR_ALREADY_EXISTS) Then
MsgBox "程序已经运行！"
End If
End Sub

u have so advanced ideas....

我记得vb是有方法判断是否已经打开了相同的文件的．

App.PrevInstance应该是属性吧，不是方法。