SharePoint 2010 AAM PublicURL change breaks User information at site collection level

Hi All,

We are required to change the URL of portal, at the same time keep original one so as to enable users to continue existing bookmarks.

Original settings:

Default Zone

Internal                                                         Public
http://servername                                           http://servername

Intranet Zone
Internal                                                         Public
https://OldIntranet                                          https://OldIntranet

New Setting for Intranet Zone

Internal                                                         Public
https://OldIntranet                                          https://NewIntranet
https://NewIntranet                                         https://Newntranet

Everything seems to be working except custom web part which usesSPContext.Current.Web.CurrentUser.LoginName

To fetch data from list based on user login name.

Everything works fine if I use OldIntranet url. I believe I am missing something on UserProfile front, not sure what & why..