The vertical scrollbar is visible in Firefox but not Chrome, but only when using virtual scrolling. For Chrome users, it's impossible to see that there is more data available like this... See e.g. here: http://demos.kendoui.com/web/grid/virtualization-local-data.html
Nope, restarting did not help. Chrome 18.0.1025.142 on OSX Lion.
I have just tested the demo under Chrome 18 (most recent version) and the vertical scroll was visualized as expected. Can you please check whether the issue remains? You may also restart your browser to see whether this helps.