Peter,
Since Telerik did not "deliver more than expected" with your last response, I decided I was on my own to resolve the issue and tried a long shot. Contrary to your statement "... I don't know of such problem with the previous version either.", there apparently is a glitch.
I upgraded to "2008.2.1001.20" and scrolling works fine.
It also had worked back in July when I did a cursory test with 2008.2.723. I set the test aside while I hosed out other fires. The dev team upgraded to 2008.2.804.20 at some point between then and now and it is that verision that seems to have an issue with scrolling.
K.E.