is inputbox still being used?

Code:
   'Dim productKey = InputBox("Enter new product Key", "New Product Registration", String.Empty)
        Dim productKey = productKeyTxt.Text.Trim

        If Not String.IsNullOrEmpty(productKey) Then
            'if product key is valid, then register the product

            Dim Lic As New License
            Lic.passkey = PassKeyLbl.Text
            Dim IsValid As Boolean = Lic.validateKey(productKey)
            If IsValid Then
                My.Settings.productKeyRegistered = True
            Else
                MessageBox.Show("Product Key is invalid")
            End If
        End If
as you can see I have it commented out on the first line.

I am using the small Licnese class in the codebank. Thanks for whoever submitted it.

Anwyas, everything works fine when using a textbox. When I throw the input box in my app hangs. for example, NO exception is thrown. the computer slows down to pretty much where I have to restart. I can't click anywhere, and if I do i gotta wait about 30 minutes until the process is executed.

Has inputbox been buggy for people before? Is there a reason Why is does that?

* I 've been using inputbox for some other sections of my app, and they seem to go okay.