I just repled to your post about your problems with NAV but it seems from the difficulties you are having with email that you did an upgrade installation & not a clean installation - the latter is highly recommended. I guess your Address Book is hiding away there in another user account. Do a search of your C drive for *.wab and this should throw up any other instances of your address book. Import the contacts into your current blank address book. Have a look at this discussion concerning lost emails after upgrade.

Upgrades usually cause problems later.
A Clean Install is recommended.
You can Clean Install form an Upgrade XP CD.

Use the below links for info on a Clean Install then install Drivers from CD with Windows XP started , just insert Driver CD.

I have shown  Supersite & Elder Geek links last as they assumes Clean Install status so doesn't include step to delete existing partition  & so achieve Clean Install status.
(Clean Install status , ie: no Windows OS installed on HD).

Use  this link & select XP Home or PRO then method , ie: Used Hard Drive , Multi_Page has text & large pictures of Clean Install.
http://www.windowsreinstall.com/

Use this link for Clean Install of XP , if you click on Pictures they Expand for easy view
http://www.michaelstevenstech.com/cleanxpinstall.html (Delete existing partition at step 10b for Clean Install)

or use this link ( *** Delete existing partition at step 5 for Clean Install ***)
http://www.winsupersite.com/showcase/windowsxp_sg_clean.asp

or use this link (***Delete exiting partition at Fig 06 for a Clean Install**)
http://www.theeldergeek.com/xp_home_install_-_graphic.htm

Clean Install deletes existing partition (like FDISK)  &  Formats HD during Install of Windows XP  from XP CD.
Set BIOS to use CD-ROM as 1st boot device usually by pressing "F2" key during boot (startup),
for some Computers press "Del" key
Re-start Computer & when message "Press any key to boot from CD" shows do it & let subsequent messages "Press any key...." time out to Windows setup.