Lol Client disappears when I click Hextech Crafting button

Sometimes when I click the Hextech Crafting button my entire Lol Client disappears except for the words "Loot and crafting inventory." If I go into my task manager Lolclient.exe is still running under processes but League of Legends is not running under applications. Also, if I try to open LoL again I get an error saying "Another instance of the launcher is running. Do you want to terminate it?" This problem seems to occur most commonly if I click on the Hextech Crafting button while I am at the "Assemble your party" screen (the one where you chose your roles before a game) or if I am in a queue waiting to be matched up.