I suggest you uninstall all VSO (and other products you have been trying to install that use the Patin Couffin driver) products using Windows Add/Remove programs and reboot.
Then navigate to C:\Program Files and delete the VSO folder (and other program install folder), open Device Manager (click Start>Run and put devmgmt.msc then click OK).
In device manager check at the bottom for "VSO Devices", if there click the + to expand it then click on "Patin Couffin Engine" to highlight it then click uninstall at the top and reboot. If "Patin Couffin Engine" is listed more than once you need to remove them all.
If VSO Devices is not listed just close Device Manager.
Do a system search for Pcouffin.sys (Normally C:\WINDOWS\system32\drivers) and delete it if found.
Navigate to the "C:\Documents and Settings[Your user name] \Application Data" folder, if the following files are there then you should delete them.
(do not delete any files other than those listed above)
You should also run a registry cleaner such as Regseeker (http://www.snapfiles.com/get/regseeker.html)
Before attempting to re-install you should first update windows by running Windows update to get all the latest patches/fixes.
Then download the latest version of the software from www.vso-software.fr/download.php, next shutdown as many running programs/processes as possible, this includes any Antivirus/Anti Spyware/Firewall software you may have running.
Then install the software and reboot again and retest.