Try uninstalling WB, first look in Windows Control Panel/Add-Remove, If you don't see WindowBlinds listed there, then uninstall via Stardock Central.
Then check for any WindowBlinds Registry Keys that may have been left over. If you find any of the following, delete them;
HKEY_CURRENT_USER\Software\Stardock\WindowBlinds
HKEY_LOCAL_MACHINE\SOFTWARE\Stardock\WindowBlinds
HKEY_LOCAL_MACHINE\SOFTWARE\Stardock\ObjectDesktop\WindowBlinds
Reboot your PC, and re-install WB.