On your Windows 2003 machine keep make sure that you have granted the
permissions needed to the correct account. You will find is you check in
IIS that the process is now running under an account called Network
Service. Also, if this still does not work, you could download regmon from
http://www.sysinternals.com and reproduce the problem will running that
tool. You can look for any access denieds and it will also show you which
account is attempting to make an access.
This posting is provided "AS IS" with no warranties, and confers no rights.
Hope this Helps
Holly