If the code you have posted is correct, you are referring to the UserName property when you are setting the UserName property. This would create an infinite recursion and lead to an OutOfMemoryException if I'm not mistaken. You should be referring to the m_UserName variable, i.e.
VB Code:
  1. Me.UserName = Value
should be
VB Code:
  1. Me.m_UserName = Value
If this is just a typo on your part, please let me know the details of the exception.