This would be because ndisgtk can't find the ndiswrapper module, which has presumably not been installed. Try "modprobe ndiswrapper" and you should get the same error. Installing module-assistant and ndiswrapper-source and then entering "m-a a-i ndiswrapper" should build and install the correct version of the module for you, but this doesn't get around the core issue of ndisgtk not noticing a lack of an ndiswrapper module.
The attached patch should partially fix this by making ndisgtk throw up a warning dialog when the ndiswrapper module is not present. Tom Parker
diff --git a/ndisgtk b/ndisgtk index f5c97cd..244985d 100755 --- a/ndisgtk +++ b/ndisgtk @@ -300,12 +300,15 @@ class NdisGTK: error_dialog(_("Error while installing.") , self.install_dialog) else: # Assume driver installed successfully. Set up and reload module - subprocess.call(["ndiswrapper", "-ma"]) - subprocess.call(["modprobe", "-r", "ndiswrapper"]) - subprocess.call(["modprobe", "ndiswrapper"]) - - self.get_driver_list() - self.install_dialog_close() + try: + subprocess.call(["ndiswrapper", "-ma"]) + subprocess.call(["modprobe", "-r", "ndiswrapper"]) + subprocess.check_call(["modprobe", "ndiswrapper"]) + + self.get_driver_list() + self.install_dialog_close() + except subprocess.CalledProcessError: + error_dialog(_("Ndiswrapper kernel module not present, please install."), self.install_dialog) def remove_driver(self, *args): """