I have an Acer emachines El321-18se that uses an NVIDIA GeForce graphics. I recently installe Ubuntu 13.04 and from time to time the screen gets jumbled and distorted. I try to recreate the issue but can't seem to do it. When it happens I have to do a hard restart of the computer as I cant use the mouse or keyboard, not sure if its because the screen has gone out or it freezes these devices. If there was music playing it stops so I am assuming it freezes everything. At times when it happens and I shutdown and restart (I have skype installed), I see the accept end user licence come for skype and I have to re enter my password. I am assuming that it has updated the software and that could have caused the problem.
I also noticed that within a couple weeks after installing the OS, sometimes while installing other software the same issue happens, also it used to happen when I open the launcher but seems to have stopped doing that when I open it. It still happens with the skype updates and from time to time when I install software.
Are there any such known bugs and is anybody else known to have experienced this?
I cannot get a screenshot as the computer is totally unresponsive when this happens.