I have just installed NVIDIA 270.41.06 on my machine, running 11.4, KDE 4.6.2, kernel 2.6.38.3.2 desktop 86x64
Video Card GeForce 6150SE
One application displays normally, but if I open another the screen apart from the top bar is black. If I reduce the application display size to about half screen the contents will appear as normal. Start expanding the application again it blacks out.
Close all applications and again, the first opened will be as normal, the second will have a blacked out main screen (just the title bar visible) until it is reduced to about half.
I looked at the link in a previous message which took me to a Nvidia page where I entered the relevant details and that took me here The supported tab shows the 6150SE.
It looks like there is more than one driver that may function here with your card. You could uninstall one version, and try the other, and then go with the one that works the best.