I am doing experiments all the time, and sometimes I stumble upon problems that other people face, often unresolved. This is my kind of challenge. For example, Ubuntu initrd problem that I faced with Jaunty way back was one of these. There were tons of online resources pointing to this or that workaround, none focused on the core issue. So my solution was completely different, and this case, it will be different, too.
Symptom: You have a computer with an Nvidia card and you installed Ubuntu 11.04 Natty. You get a prompt for Additional Drivers, which displays the proprietary Nvidia driver available for download and activation. You do that. You reboot. But on the subsequent login, the Additional Drivers manager pops again. It reads Nvidia driver is activated but not currently in use. What do you do now?
Or rather, understand IF you have a problem. After seeing this error, you will most likely go online and search for a solution. Instead, you will find a hundred unanswered forum threads, mailing lists and bug reports, each ever so slightly different from the other.
Now, let's try to analyze the problem. It says your Nvidia driver is activated, but not in use. This means that you're not utilizing your card? Or are you? How can you check that? Well, there are many possible ways, so we will try them all.
This is your first station. If you installed a proprietary Nvidia driver, you will also have the control panel available. Fire it up. Normally, when no Nvidia card is found or the driver is not installed, this tool will popup an error messages. See if this happens.
In my case, no such issue. The driver seems to be working fine. Hmmm.
But perhaps this is some Unity bug. Let's see if Unity supports our card. To check this, you can run the /usr/lib/nux/unity_support_test command with the -p flag, as shown in the screenshot below. Seems like we're ok. Another giveaway is the ugly 2mm background see-through border, which only happens if you're running the Ubuntu Unity Compiz plugin, which only happens if you're running Compiz, which only happens if you're running a proper 3D graphics driver. So the plot thickens some more. It's a soup already.
Ah, now you recall my Linux configurations article from five years ago, still valid as the day it was written. We will check if the Nvidia driver (module) is loaded and in use. As it turns out, not only is it loaded, it's in use some plenty.
I was beginning to fully believe the error message is a glitch, at least in my case, and probably many cases out there, not a real problem with the driver. Moreover, I did uninstall the Nouveau driver before I even started troubleshooting, so I'm not getting any magical help. BTW, to uninstall the open-source driver, run:
sudo apt-get --purge remove xserver-xorg-video-nouveau
Back to my testing and checking, I enabled all kinds of Compiz plugins and fired up the bells and whistles. My Nvidia card was working as it always did, pure and true, despite the message in the Additional Drivers window.
So someone is lying, and it's not me or my card. Therefore, if you get this far and see the same results as I do, then the problem is most likely in the Additional Drivers reporting facility or whatever, so calm down and enjoy your computer.
What's the lesson of this short howto? First, don't sheep-panic. Second, don't blindly follow online advice. Someone has a similar error message to yours, that does not mean they have the same problem, if at all. In this case, this is clearly a bogus error. But most importantly, you need to know how to approach and troubleshooting issues like this one.
This article teaches you how to follow the train of logic and fix your problems without going overboard with fear or despair or random copy & paste of online solutions. For example, we learned this was a bogus error message. Nothing more than that. We examined the driver setting utility, we checked the system compatibility, we checked the kernel module is loaded and in use, and we tested with Compiz effects that put the card to some hard labor. All is well.
Like Tolkien says, not all that glitters is gold, not all drivers are touched by the cold. So please, go back to your setup, run the simple test above and check whether you're facing a real issue or a naughty and misbehaving report. Party on.