I've downloaded the gnome-shell theme extention. Using the default theme has no problem, but as soon as I try using one of the themes, clicking the "windows" key, then writing something to start searching for it, and the X server gets stuck. I'm using Ubuntu 10.11, with gnome shell verion 3.2.2 Thanks for your help Yair
As Gaurav_Java already said, there is no fix as it is right now! This problem started with Gnome-Shell v3.2 and is mostly related to Nvidia drivers.
You can install this Shell-extension, called "Disable Search", which does not resolve the problem itself, but simply disables the search function and therefore the crashes of X server (meaning: you don't have to force your machine to reboot every time).
Hopefully there will be a fix soon!
This is not the FIX soution for this . u must try restarting shell to do following do this:
this will help u restarting shell . may be this would help