I'm using PHPStorm 7.0 in Ubuntu 13.10
I have problem after run command "Next Occurence" / "Prev Occurence" via keyboard shortcut "Ctrl + Alt + Down Arrow", I can not type any word or run any shortcut again in PHPStorm in any view (editor, Project, Favorite, etc), like PHPStorm ignored my keyboard input. But fortunately it still can accepted mouse input, so I still can save my works, then I restarted it & back to normal.
In my Ubuntu I have modified 2 keyboard shortcuts,
Ctrl + ALt + Down to Disabled
Ctrl + ALt + Up to Disabled
Is this problem with PHPStorm or Ubuntu?
After asking PhpStorm Support, I was suggested to use other type of JDK. He said because of a known bug for OpenJDK that should be fixed in the next minor IDEA release
Here is the link related http://youtrack.jetbrains.com/issue/IDEA-79312
Then I tried to change using IBM JDK, but the problem still occured, and even make phpstorm quite slow. Step by step how to (note this dont solve my problem, just FYI) : http://www.wikihow.com/Install-IBM-Java-on-Ubuntu-Linux
From my point of view, PHPStorm has some problem with OpenJDK with different behavior. Mine is as I stated in my question. In addition, this problem happen not only after Find Occurence or using keyboard shortcut, but happen when I did nothing, it just happen pretty often.
Next I tried with oracle JDK, suggested with above link. Step by step how to : http://www.wikihow.com/Install-Oracle-Java-on-Ubuntu-Linux
Then the problem didn't occur again, after I have tested using a day without problem, so I write this answer.
Good Luck