Windows 7: keyboard has like "intervals" between letters

This is the 2nd time this happened.. Whenever I type, the keyboard has like "intervals" between letters.. I am typing this really slow to be sure all the letters are complete..
This is what happens if I type at normal speed:
The quik brow fox jus oer th lazy og..
i will press "d" 10 times at like 2 per second, this is what happens:
dddddd
if i hold "d" for 5 secs, this is what happens:
d
even holding down the "down arrow" to scroll, it only scrolls once (exactly what happens if u press down)
"d" is just an example. this happens to all the keys.
This is a laptop.. specifically HP Probook 4530s
What could be wrong guys?