C'est bon laissez tomber, j'ai trouvé comment faire :
En fait mon disque externe était tombé en rade, pourquoi ? L'EEPROM du boitier était fichu. Fallait donc le reflasher.
Mais je n'arrivais pas à réinstaller le driver, et j'ai utilisé cette technique

:
Another solution, this one from Niels in the Netherlands:
Step 4 - Install new hardware.
This one gave me a serious headache because Windows XP PRO simply refused to auto-install the driver when I selected c:\PH-1003 EE SW\Driver as the folder to look in. Also it didn't give me any options to manually select the driver and install it.
So after a moment of panic I came up with the following solution:
1. Go to control panel and select "Add Hardware". Note: this part can also be with the auto-install popup.
2. Now instead of selecting a folder in the "Have Disk" part, select the "Choose device from list" (or something like that) option.
3. Once you're there, select "Universal Serial Bus Controller" and THAN use the "Have Disk" option.
4. Go to c:\PH-1003 EE SW\Driver (or where ever you put it) and select "CyUSB" and click OK.
5. NOW it will show you the correct driver (which can be manually selected for install). Go ahead and install it (you'll get some warnings from Windows, but those can be ignored).
So that would be the way to manually install it when the auto-install function refuses to do it. Hope it saves someone some time, because it annoyed the hell out of me (knowing that there is a manual install function, but not being able to find it).
http://daltrey.org/linux/cypress.html
Le driver a été installé, j'ai pu reflasher l'EEEPROM, j'ai de nouveau un disque externe
