Yesterday I tried to update the driver for my 9500 GT, only to have it bomb out midway. On top of this it seemed to completely uninstall my older driver, and the card was showing as unknown device in the device manager.
I tried updating drivers to no success, windows updates weren't working either but worked after I ran a bunch of registry cleaners. Then I had the idea to install nforce, which lets my computer recognize my card, but I think the driver is still busted as anything that requires nvoglnt.dll won't start and I get a blue-screen about nv4_disp if I try and run graphic-intensive programs.
Windows is still trying to update my graphics driver, whenever I restart it will try to install but abruptly shuts off, when I reboot and log in Installshield tries to run but shows this message:
@windows service pack 1 (6001) bt_other 0.0"
along with another window mentioning error code -5001
I can't uninstall service pack 1 to try and repair it, service pack 2 won't install.
Sorry if this is too wordy, I'm hoping all this info will help get a solution that doesn't require a clean boot of windows.
I met a very similar problem (setupdll.cpp (391)) when I was installing my Realtek audio driver. It is because the name of my user folder is IN CHINESE (c:\users\心锐).... furthermore, if any of the directories involved in the installation processes whose name is IN FOREIGN LANGUAGE (setup file folder, extracting folder, configure file folder, etc.), that might cause an error.
I am not sure if we are on the same boat. If your user account name is not in English, i would suggest u create a new account (don't forget to set it to an administrative account) with English folder name, and abandon the current one u are using.