I created a simple test with SendKeys, and tried both SendWait and Send.
Private Sub Form1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handle
In your app settings (app.config in a Visual Studio solution, or when located side by side to the application), add the following as child of the element:
If that doesn't work, try:
Source: SendWait() [MSDN]
"... As a result, the SendKeys class may behave differently on different operating systems ..."