Outlook cannot access registry

I installed Outlook under C:\program files\microsoft office\ on Windows
XP(c:\windows) long time ago and it worked very well. But recently, my XP
crashed and in order not to affect the important files I left the WinXP there
and installed a fresh Windows 2003 in the same disk partition under a
different folder(c:\win2003). And Outlook is installed in the same
folder(c:\program files\microsoft office\). After that, when trying to
create a new pst file from outlook, I got an error "There was an error
accessing your system registry."

I know there could be some conflicts for the two system installed on the
same partition, but I can not figure out why outlook can not create pst file
or a new e-mail account.

Any help would be appreciated.