If your entire computer is freezing and has to be re-booted (as opposed to Lightroom stopping but the rest of the computer still works), this is almost always a hardware malfunction or bad video driver. There is no way for software to make the entire computer freeze and need to be rebooted in the absense of hardware malfunction or video driver incompatibility.
It does not freeze every day, but in a particular time it does and i could also not be working on Lightroom but just watching Netflix or looking on Facebook (with Lightroom in stand by), i'm very surprise of their answer, what i'm doing now is uninstall Lightroom for 2-3 days and see how it's work without it, that was the "Genius" Suggestion...
It does not freeze every day, but in a particular time it does and i could also not be working on Lightroom
Sounds to me like it has nothing to do with Lightroom. Which is what I said earlier. You have either a bad video driver or some hardware malfunction.