Version:           2.1 (using 4.1.3 (KDE 4.1.3), Kubuntu packages)
Compiler:          cc
OS:                Linux (x86_64) release 2.6.27-9-generic

I first noticed this in oKular but I have since noticed it in Konsole and Konqueror.

In oKular, while viewing a pdf I can scroll down initially with no problem.  However, scrolling up (one click) after having scrolled down causes the oKular to continue to scroll down for one click.  Subsequent scrolls in the same direction will handled correctly.  When the direction of scrolling is changed again, the glitch will repeat.

In Konsole everything works fine until the window becomes full and the scroll controls become functional.  As soon as the first line of text scrolls up and off of the page, I may get a CR and LF but no prompt, or the display might show a CR/LF and the previous command but pressing <enter> just results in a newline, or the first <enter> may seem to go to a bit bucket while the second <enter> works normally.  Very unpredictable after the scroll buffer goes to work.  I'm using xterm instead and it works perfectly.

In Konqueror listbox scrolling behaves oddly.  As I type this, when the listbox got full and the control needed to scroll, my first <enter> did nothing, the second <enter> jumped two lines.

I am using the default installation of kubuntu intrepid.  Some funky desktop features (like wavy windows while dragging) are enabled by default.  Maybe this problem is unique to those settings as I haven't noticed anyone else complaining about something that has been (more than) annoying me for a few weeks now.  Previous install, Kubuntu Hardy w/ KDE 3.5-ish, did not have this issue.