Recommendation: Toggle subclassing. Since you are comfortable that the hyperlinks are working, don't subclass until you want to test that functionality again. Before you compile the application to an exe ensure you toggle subclassing on.

1. In your form's declaration section, add this: Dim bSubclass As Boolean
2. Tweak your Form_Load to
Code:
bSubclass = False ' change to True to activate subclassing; when activated hope no errors & don't hit End

' your other code
...

If bSubclass Then
   glngOriginalhWnd = Me.hwnd
   glnglpOriginalWndProc = SetWindowLong(glngOriginalhWnd, GWL_WNDPROC, AddressOf RichTextBoxSubProc)
End If

....
3. Your Form_Unload...
Code:
If bSubclass Then
    bSubclass = False
    SetWindowLong glngOriginalhWnd, GWL_WNDPROC, glnglpOriginalWndProc
End If