Keyboard Dodge Inconsistancy

I'm posting this to see if anyone else is having similar problems. I'm having trouble with my roll. Now, some of you are probably thinking : this guy just doesn't know when to roll so he's pressing it late and getting hitting before he can roll. Well... I been trying to do rolls in an empty field with nothing to hit me.

Anyways here's what I'm experiencing. When I try to role either forward, back, left, or right, it generally works fine. However, when I'm running diagonally, a lot of times my roll doesn't happen and the guy just keeps running.

I'm using WASD to move and space bar to role.

When I'm running forward and right, W+D for my configuration, the space bar triggers a role about 2/3 of the times. That's right. Roughly every 3rd role gets ignored.

When I'm running forward and left, W+A for my configuration, the space bar triggers a role less than 1/4 of the times. Yeah... I need to hit that space bar at least 4 times before this guy rolls.

Anyways this is obviously making it very difficult to play, so I was wondering if anyone else is having this problem and possibly knows a fix.

A few other things:
My game is not lagging.
I am not out of stamina when I tried to roll.
I don't think it's my keyboard because I tried this test :
http://www.microsoft.com/appliedsciences/content/projects/KeyboardGhostingDemo.aspx
and it registered W+A+space every time.

Sometimes it is kinda frustrating to get a nice running jump for the Lower Undead Burg shortcut, but otherwise I just use target lock and rolling straight. By the way, getting an early Havel's Ring, dodging his attacks involved diagonal rolls. It did sometimes ignore A button (and I drop to his feet insted of getting behind), making me get smashed. But never Spacebar. And yes - I hit Spacebar several times, just to be sure I get the roll

I haven't experimented with running jumps much, but that is an interesting thought. I was doing normal rolls.
I'm not sure about Havel. I parried him to death.

I did most of my testing at that open area outside of demon ruins after the lava is drained.
I did my testing there because... well... I was in the area after dying to the Taurus demon because I couldn't roll properly.