Client closes on start

Hello,

It's the second week with an issue with the client/account where regardless of the method I use to start it ( client/launcher executable, administrator run or not ), it closes soon after the loading screen window comes up, shortly after I open it.

I've tried reinstalling/repairing it manually or via Hextech Repair Tool without success. Restarting the PC or trying to close the process under end task ( details ) doesn't do anything. Deleting certain files including the executables doesn't help either but reinstalling does the trick sometimes, once out of 3-4 attempts.

Does anyone have other suggestions for a fix?

Thanks