It looks like some sort of registry error but what you do about it (or whether it's even worth doing something about it) depends on several factors.
Firstly, try launching 'Help' from the Start button. If you can access it that way then it's simply the shortcut from the F1 key that's dud. I probably wouldn't bother trying to fix it and simply stick to going via the Start button.
Next, do you know how long it is since F1 worked properly? If it was quite recently, using System Restore (from Start > All Programs > Accessories > System Tools), to take your computer's registry back a short while should fix the problem. However if it's several years since you last pressed F1, System Restore probably won't help much!
Beyond that point you're looking at possibly doing a 'repair' installation of Windows 7, which is quite a drastic step for a fairly small problem, so I wouldn't rush into it. I rarely use 'Windows Help' anyway because it's so hard to find what I actually want. Googling is usually faster!