Touchpad two-finger scroll scrolls down instead of up

Version: 2.0b4 on MacOS 10.5.6 Intel.
Server: RealVNC 4.1.2 on XP SP3, admin-enabled account.

1. Connect to the server.
2. Open a window with a scroll bar -- a browser or command shell, make sure it has enough content to scroll -- do a Google search, do "dir" a few times.
3. Scroll down and up using the touchpad with two fingers.

Expected: scroll as we know it.
Observed: scroll down works fine, scroll up scrolls (mostly) down instead of up. Sometimes it does have an enlightened moment and scrolls up a bit, but most of the time it scrolls down.

Mouse wheel works fine, only touchpad two-fingered scroll has this issue.