The underlying provider failed on Open

Question

I am using a Windows form application with ADO.net entity model 3.5..

I get the Error message, "The underlying provider failed on Open" with the underlying message "An attempt to attach an auto-named database for file C:\Users\Khurram\documents\visual studio 2010\Projects\EmpManager\EmpManager\bin\Debug\main.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share."

I'm just getting started with ADO.net, so this may be a very Noob'y question. This is the part of the code that the error is at.

      Using MyData As New XCo
          Dim Emps = From x In MyData.Employees Select x

          Dim AvailableEmps As New List(Of Employee)
          For Each Emp As Employee In Emps    'Error Here
            If Emp.Name.Contains(TextBox_SEARCH_EmployeeName.Text) = True Then
              AvailableEmps.Add(Emp)
            End If
          Next

          If AvailableEmps.Count = 1 Then
            LoadEmployee(AvailableEmps(0).ID)
          ElseIf AvailableEmps.Count > 1 Then
            Dim ssd As New SearchSelectDialog
            ssd.FoundEmployees = AvailableEmps
            ssd.ShowDialog()
          ElseIf AvailableEmps.Count < 1 Then
            MessageBox.Show("No match found", "information", MessageBoxButtons.OK, MessageBoxIcon.Information)
          End If
        End Using
      Else

Hope someone could help me, Thanks..