Rviz and rqt crash when trying to save

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Hi, I have been using rqt-rviz to see the data from my kinect (via openni) but everytime I try to save a file, any kind (image, configuration file,etc.) the "save as..." window opens but it doesnt load nor say anything, just gray. And my ubuntu screen gets darker (like when programs crash). When I type CTRL-C in the terminal I get this error:

[ INFO] [1365896813.550288513]: OpenGl version: 3.0 (GLSL 1.3).
python: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.
python: /usr/include/boost/thread/pthread/recursive_mutex.hpp:92: boost::recursive_mutex::~recursive_mutex(): Assertion `!pthread_mutex_destroy(&m)' failed.
Aborted (core dumped)