Reply #3: Looks like a popular error [View All]

[DaveJ]

Are you sure you do not already have administrator privileges? I think the problem may be something else.

I Googled that error and found a lot of results, with at least a couple different solutions:
http://www.google.com/search?q=%22canceled+due+to+restrictions+in+effect+on+this+computer%2C+please+contact+your+system+administrator%22&rls=com.microsoft:en-us&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1

One said it may be Anti-spyware program blocking registry access. Try disabling anti-spyware temporarily.

Also, MS as an article with steps to take if you feel comfortable with the registry:
http://support.microsoft.com/kb/823057