Hello Yohann
The problem encountered with Matisse ("tasklist is unknown" ) is probably due to the version of Windows you have. Tasklist is a windows program but for example it's not distribute with the Windows XP familial edition.
In order to solve such problem, I modified the perl script used to run matisse.
Replace the old version in the bin directory and try.
Another solution is to download tasklist (
http://speedweb1.free.fr/download/utilitaire/tasklist.exe) and place it in C:\Windows\System32\ or in the bin directory of Telemac
Regards