Stepmania input problems

[Dancing Mad]

Prior to having to update the driver for my video card to keep my computer from crashing while tryinig to watch youtube videos (and even mundane things like viewing images on other websites), I had no problems with the timing of playing Stepmania either by PS2 controller or even my keyboard.

Now, since updating said driver, no matter what input method I use to play Stepmania, there is a VERY obvious delay between a button press and the game reacting to it. What would normally be a perfect or marvelous, which I could get by pressing the button at the exact moment an arrow crosses the target bar, becomes a great or worse. I'm not sure of the exact delay in response, but I have to hit a button very noticably early to get it to register as a perfect or marvelous.

Does anyone have any idea what I can do to fix this?

Edit: Stepmania is the only program that has such a delay. All of my console emulators and other game programs have no such problems.
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I'm still a newbie to DDR, no matter HOW good you think I am...considering how long I've been playing compared to everyone else.

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