problem with getclick

I am using Psychtoolbox 2.5 with Matlab 6.1 for Windows.
I have got a problem with getclicks.dll
The message is
Error in Getclicks.dll
GetMouse failes to create direct input object

I tried to use the older release (2.45) of Psychtoolbox and it works

I copy getclick.m and getclick.dll from 2.45 in 2.5
It seems to work one time and after the matlab.exe takes all the cpu
and do nothing

Does any
one know about this problem? Thanks to any one that can help me.

Sincerely,
Pascal Percevault
Cnrs marseille