whats the program you are trying to uninstall?
it could be the program is running and cant be uninstalled or other programs are interfering with the uninstall process.
you can always remove it manually but i would try removing it in safe mode first,were there will be a minimum of processes running.
to get into safe mode,restart the computer and watch the screen(you need to be quick)
tap F8 when you see the prompt at the bottom,it will take a moment or two and things may appear to be slower than normal in safe mode,dont worry about this.
go to add remove and try now.