Problems with Language Cloud

I am using Trados Studio 2015.  I have been getting the message: "Object reference not set to an instance of an object". Then after Trados crashed today I could not access to Language Cloud anymore. I tried renaming the 12.0.0.0 folder as they suggested in another post  but when I restart Studio it asks me to register and then a message appears: "Connection to Language Cloud failed". Studio has been crashing the last couple of days and different error messages appear but until now I could use Language Cloud with no problem. Please help me, I am in the middle of a project!