Permanent App crashes in OSX Capitan

I was a happy MacBook Pro (13-inch, Early 2011) user, till about couple of weeks ago installed OSX EL Capitan. Suddenly several my dear applications stopped working, for instance SideSync, ClearView, Steam, AVL. An application starts and then exits in a second without any message. Is my machine just an old one and I need (can I safely?) better step back to previous OS? Thank you very much in advance.