I just updated to 7.0.1 from 7.0.0 to solve the well-known latin keyboard issue. The first time started Mathematica after updating, it ran fine. But the day after, it wouldn't: it opens the front-end, the "Welcome to Mathematica" dialog, and then, total freeze. Only way out is to kill it. The MathKernel process however, is still up and running ("sleeping"), although it doesn't appears on the license server.
I thought it could be an issue with SELinux as it coincide with a SELinux update, but no since switching to Permissive mode doesn't solve the problem (and SELinux would probably have complained).
I'm running Fedora on a 184.108.40.206 Linux kernel.
Thanks for your help,