My graphic card is a Nvidia GT540M gDD3 1GB_Hybrid on an Ubuntu 12.04 install.
Installed Ubuntu one day ago.Yesterday it started without any problem but since today I get "The system is running in low-graphics mode". I know this was explained here (How to fix "The system is running in low-graphics mode" error?) but I have done everything and the problem is still there. I can access the system by using Shift during booting, after that "previous linux versions" - "Ubuntu, mit Linux 3.8.0-29-generic". There were like more than 200 updates, so I guess it has to be related to the updates? (just guessing..)
Even though I can access the system, I tried installing the drivers through Terminal, but apparently nothing was changed.