Windows 7 "Run as administrator" has stopped working

My computer is not running any programs as administrator. I am logged in as Admin User but when I try to run a program as administrator, nothing happens even though the program itself will run. It was working fine when i turned on my computer for an hour or so, after that i noticed that none of the programs can run as administrator. I've also tried right clicking a program to see if it can Run as administrator but still won't work. I also checked my UAC settings to see if its turned on, and it is. Lastly, I've ran a system restore, and still nothing has changed. I don't mind if i can't Run as administrator, but there are programs that I use daily. Those programs need to Run as administrator in order for it to work. Is there something I turned off that is preventing me from Running as administrator? Or do I have a virus on my computer? Please give me some suggestions/advice on what I should do to fix this problem.