apt-get purge … and
apt-get remove … things seem to not work ! :\
There are some effective weapons such as
sudo dpkg --remove --force-all libvdpau1:amd64
sudo dpkg --purge --force-all libvdpau1:amd64
but somehow useless here ...
In the end ... the solution was just as simple as
sudo rm /etc/vdpau_wrapper.cfg
sudo apt-get install -f
And no - you can not install newer drivers than 304 - they do not support GeForce 6150 SE GPU !
I have a pc with an old Geforce 6800 card and I have managed to successfully install the 32bit Nvidia 304.137 driver for it on Lubuntu 18.04; all thanks to a community patch. Here is the procedure.
Install build tools
$ sudo apt install gcc make build-essential gcc-multilib dkms mesa-utils
Download driver from https://www.nvidia.com/Download/driverResults.aspx/123708/en-us
Download patch from https://adufray.com/nvidia-304.137-bionic-18.04.patch
Extract archive, place patch into extracted folder and apply patch
$ ./NVIDIA-Linux-x86_64-304.137.run -x
$ cd ./NVIDIA-Linux-x86_64-304.137
$ patch -p1 < nvidia-304.137-bionic-18.04.patch
Disable nouveau driver and reboot
$ sudo -i
# cat << END > /etc/modprobe.d/disable-nouveau.conf
options nouveau modeset=0
# update-initramfs -u
Bring up terminal with Ctrl-Alt-F1, login
$ sudo -i
# service lightdm stop
# init 3
Install NVidia driver
Ignore the first warning about preinstall failing, agree to driver recompilation on kernel update and to configuration files update. Reboot.
Driver should be working now. Check with the following:
$ lshw -c video 2>&1 | grep driver
There is one small problem though. Apparently Nvidia driver installs it's own version of libvdpau, which does not work with mplayer. That's why we need to forcefully reinstall libvdpau (and possibly need to do this on kernel update, because driver will recompile and reinstall it's own, non-functioning version for this library?)
$ sudo apt --reinstall install libvdpau1
Compiling nVidia 304.137 on Ubuntu 18.04: https://adufray.com/blog/2018/06/02/nvidia-304-127-on-bionic
How to install NVIDIA.run?: How to install NVIDIA.run?
PS: This post is basically a duplicate of my post at ubuntu-mate.community, but since installing 304 Nvidia driver on Lubuntu 18.04 is a very common problem, I have decided to make additional post on askubuntu.
I found that the correct driver (working well now for two days) is the nvidia-304 which can be installed from repositories. This might be problematic if you are making a clean install because the Geforce 6150SE will not work well when installing from the Ubuntu DVD: the Ubuntu live session will freeze, so follow this sequence:
Update your system:
sudo apt-get update
sudo apt-get upgrade
Install the driver:
sudo apt-get install nvidia-304
DO NOT run
nvidia-xconfig(THIS IS IMPORTANT).
Nvidia X server settingsfrom the dash.
I hope this helps others, it's worked for me (so far).