XP SP1 will not install "Access is Denied"

[Erin]

I am receiving the error, "Access is Denied" when trying to install service
pack 1. I have located the svcpack.log file and it contains the following:

Copied file: C:\WINNT\System32\pidgen.dll
***

Num Ticks for Copying files : 567421

***

INF_REGISTRY Failed
***

Access is denied.

***

Service Pack 1 installation did not complete.

Select 'OK' to undo the changes that have been made, or select 'Cancel' to
quit. If you select 'Cancel', your system will be left in a partially
updated state and may not work correctly.
***

Starting process: C:\WINNT\$NtServicePackUninstall$\spuninst\spuninst.exe
/~ -u
***

I have tried uninstalling software, changing my permissions (which all
seemed to be at full control in the first place) but nothing seems to be
working.

I am installing sp1 off of a network install file located on the local
machine. I have had success using this file to update other machines. This
is an upgrade from Windows 2000. I have tried installing from safe mode,
and get the same error.

 

[Bob Harris]

You need to be logged in as the PC's administrator to change the registry,
which this service will certainly do.

 

[Erin]

Yes, I am logged on as the administrator. I have checked the permissions
listed by the Windows help files and they are set to full control.