Interface delay with NVIDIA driver

I am experiencing a strange bug with a new installation of Ubuntu 14.10.

It looks like I/O events are processed with a delay. That is, every event from either the mouse or the keyboard (both USB) acts like the previous event. Let me give a few examples:

• I am writing. As I press a key, the character of the previous key appears. When I stop writing, to make the last character appear, I have to do something like cliking or moving the mouse.
• Or maybe I am inside Nautilus, and file foo is selected. I click on file bar, and Nautilus still shows foo selected. Then, as soon as I move the mouse, the selection switches to bar.
• I am reading a file, scrolling with the mouse wheel. I make a few scrolls down. Then I make a single scroll up, and the file still scrolls down. I move the mouse and it scrolls up.

Sometimes, but not always, the event is processed even if I do not touch the mouse or keyboard, but with a few seconds delay. Also, there are periods when the bug does not happen and I can work smoothly, then all of a sudden it reappears.

The bug seems to appear only when using the official NVIDIA drivers for my video card (an NVIDIA quadro 4000), which I need to work with CUDA (I am not sure - I may have been lucky the moments I was using nouveau). It happens both with the NVIDIA drivers in the Ubuntu repositories (v331) and those on the NVIDIA site (v346). It happens both with Unity and Gnome shell. I also reinstalled eveythigng from scratch and it still happens.

At this points, I am not even sure what to look for. It seems related to some form of buffering, but I h ave no idea what this has to dot with the video driver. Any ideas?