As a matter of fact you are the second person (and that is only among those with whom I’ve spoken here on the forums) who had problems with the dissapearing scrollbars. The other guy was using a stylus as a pointing device and also relied on the bars to scroll the content.
The solution is pretty simple though, I don’t know why WF didn’t implement it from the start. Show the scrollbars on hover not on scroll event. The bars are tiny and not intrusive any way even when they are over the elements in the panel.