Found this page:

*
u8untu.blogetery.com/.../
*

Basically, there were two options ...
*
Remove those silly ayatana scrollbars

If your scrollbars were changed by the recent Natty upgrade, you can remove
them like this

Open Synaptic >> search for liboverlay >> remove

or

sudo apt-get remove overlay-scrollbar

This removes the silly overlay scrollbars which turn a simple one-click
scroll into a two-click scroll.*

I first tried the apt-get option from the command line, then restarted, but
this didn't appear to work. Tried the synaptic option, logged out and in
again - bingo! Happy-happy-joy-joy! Real, usable scrollbars!

Hope that this helps others out there ...