Access denied to Administrator

I am running an HP Pavilion Lapton, Windows XP Home Edition 2002, SP2. I have
several user accounts set up for my family. I am the administrator. I have
been having issues with the pc clock. It keeps changing back an hour. I have
the DST checked off. I have run all the patches I thought I could find. It
still changes back an hour. (This is affecting my calendar when I sync it). I
tried to do the following (as per
http://support.microsoft.com/kb/555440/en-us) Execute the following commands
in the same sequence:

net stop w32time
w32tm /unregister
w32tm /register
net start w32time

I open a command window (start, run, command)
When I try to run the unregister command, I get an access is denied error
0x80070005

How can I get this to work? Is there another way to fix this problem? I am
in Upstate NY which is in Eastern Standard Time. When I run the update time
command (double click the clock, go to internet time, automatically
synchronize is checked off. Server is time.windows.com, I click update and it
will update but it doesn't change the clock to the correct time. It just says
updated successfully. Note: when I change the server to time.nst.gov, I get
an error that says an error occurred while windows was synchronizing with
time.nst.gov)

Thanks for any help