touchpad hangs under X4

[Christian Rehn <rehn@in.tum.de>]

I've upgraded my Acer Travelmate 516TE to X4 (I think its a gpm
problem but it worked under xfree-3.3.6).  Now my mousepointer
sometimes hangs for a few seconds and after that works as usual.

The laptop has a Synaptics touchpad and I have installed gpm 1.19.3-4.
I start gpm with the -t synps2 option.  The Pointer section in my
XF86Config-4 file I set the "Device" to "/dev/gpmdata" and the
Protocol" to "IntelliMouse".

When I try to read directly from /dev/psaux under X (in addition to
deactivating gpm) the mousepointer is uncontrollable just running
around on the screen (I tried to select different protocolls but
without success).

* Has someone a similar problem or even better a solution for my
  problem? 

* How do I downgrade to xfree 3.3.6 under Debian? (I could not find
  information on downgrading in the apt and dpkg man pages or in
  /usr/share/doc)

Cheers,
Christian