In vb 2008

What you will need.

2 button
1 text box
Timer1

Time to code!
---------------------------------------
click button1 rename it start
click button2 rename it stop

Now double click on start and add this

Timer1.Enabled = True

Now double click on stop and add this

Timer1.Enabled = False

Now double click on timer1 and add this

On Error Resume Next
SendKeys.Send(TextBox1.Text)
On Error Resume Next
SendKeys.Send("{Enter}")

and that's it enjoy your spammer