I have been having this problem for quite a while now, and I thought it was a problem with my keyboard, however upon getting a new keyboard today I'm experiencing the same problem.
The zero key on my keyboard doesn't seen to do anything, however when I press shift it does produce a ")." I am not experiencing this problem with the zero key on the keypad, that works fine.
What I have noticed when I press the zero key while I'm typing is that is seems to remove the ClearType or something. Screenshot
The Ds are before pressing zero, the Gs are after.
Any help would be greatly appreciated. This is driving me crazy at this point.