As always: Update Flash Update your browser Update your computer Update EVERYTHING!!!
If the problem persists, do what Plokkey said and Graham. Optionally, you can do their way first. Or refresh (If that was the problem, you can laugh sadly) the page.
Try pressing F11 on your browser, it should make some space. Can you post a picture?
Doesn't work if he has a Mac (He didn't tell us, making problems of the problem).
I have a Windows computer (Vista.) Some games that have cut-off screens (on the top and sides) are: Weapons, The gun game (Which is actually cut in), and others (that I can't think of right now) espiecially miniclip games.
As for the gun game the outline is inside the border of the game, so you can acually get out of the games screen (which is the oppisite of the other games where you can't even get to the outside.)
It usually is. When you adjust the zoom, the framesize will change but the size of the flash game may not, leading to a smaller frame that covers part of the game or a larger frame that shows extra stuff.