There's something strange I've always noticed in pc football games: whenever I try to kick to the upper right direction, it just won't work. All the times I use the up and right arrow keys, pressed at the same time, the ball isn't kicked.
I think this is very odd. Especially because if I use, for instance, the up and left key, THAT will work.
It happens in Fifa 99, Fifa2000, and they're not the only.
It doesn't work in any circumstances, wether it is the goalkeeper holding the ball, a player in the pitch, or a penalty kick... it never comes out!

Does it happen to you to guys? And if it does, why does it?

It doesn't make sense...

sounds more like a propblem with your keyboard, dude. try another keyboard and see if it still happens.