It was Norton protecting the registry from changes. Your post was so slim that I can't tell if this applies or you have some other protection software.
I have a strange problem. The power options dropdown list in the display dialog box keeps resetting to "portable/laptop" and "home/office desktop". That's all. Not even the original "always on" etc. are there. When I put them back, the next time I go to set a monitor timed/off setting, it has reset to the first two I listed above.
I am running XP home sp3.
P.S. I am new to this forum and want to add my PC configuration, but I don't see that option on the "edit preferences" page.
Thanks for the help, Keith.............