"RIOT CLIENT" NOT WORKING

I first encountered this problem last night.

In the "Riot Client", not the actual league of legends client, after I sign in and hit the PLAY button a message appears saying "League of legends failed to launch: something unusual has happened while trying to launch league of legends,Try closing and restarting. If the problem persists contact us at league of legends support".

I tried: restarting client multiple times restarting computer multiple times hextech repair tool repatch and then finally a complete reinstall

After the 2 hr reinstall it worked fine, HOWEVER i logged on this evening and found it coming up with the same message again. Im not keen on reinstalling every afternoon so does anyone have any ideas for fixes?

cheers guys