|Normally, that's probably a message you get if the User profile you're using does not have full Administrator rights. |
E.g. if it's a computer you don't own at an institution or business, some users or all users other than the Administrator may not have those rights, or if you're using the Guest account on any Win 2000 and up computer.
If you ARE supposed to have full administrator rights, then you probably have the symptoms of malware.
Do you have other symptoms?
If so, tell us about them.
E.g. there is malicious software that can be installed by you merely visiting contaminated web sites that was made by the makers of what's generically called "rogue" anti-malware software - the symptoms are FAKED in order to try to get you to buy their software. If you have that, along with that, you get frequent messages about your computer being infected, urging you to scan your computer with certain anti-malware software for free, and, often, there are also icons on your desktop that you did not install that are shortcuts to certain anti-malware web sites, and, often, when you try to use your internet browser it automatically goes to a certain anti-malware web site instead of your normal home page.
If you do give in and scan your computer with the anti-malware software you were pointed to, it does find crap, but at least some of it was installed by the makers of the software, and you have to buy the program to get rid of what it finds.
Most legitimate anti-malware software can't properly find and get rid of all the crap installed because what is installed is changed frequently - you must use software that specializes in getting rid of it - e.g. Malwarebytes, sometimes you need to use Smitfraudfix as well.