I have encountered this weird issue today. I didn't install or reconfigure anything to cause this. I've restarted my computer but this hasn't cured the problem.
Regardless of the application I use (I initially noticed this issue in my IDE and then checked if the same problem reproduced in other applications and yes it does - in IE/Chrome) when I scroll down with my mouse scroll wheel everything is good and I'm able to scroll all the way down. But when I scroll up (say, a long page or a code file) it will not scroll all the way up and get stuck at some point as if it has reached the top of the page when in fact it hasn't and the scroll bar on the right will stay in correct position indicating I haven't reached the top of the page yet.
It's windows 7 and I'm out of ideas for what this could be. Any ideas?