Thanks Cytan, I looked in the Plugin directory of Firefox and I found the file Except.log. The file contains at the end this message:
F:\PROGRAMMI\PMW-FX-2.0.0.13.EN-US.OS2\FIREFOX\FIREFOX.EXE
Thu Jun 19 12:22:34 2008
---[Exception Information]------------
Access Violation (hardware generated,portable,fatal)
Read Access at address 00000000h
Exception Address = 1d47a5b7 <FLASHWIN> (#4650) obj #0:001ca5b7
Is the crash of the Flash plugin connected to the Single Input Queue of the WPS? I am just asking, I am not an expert.