Yeah, I had the same issues when I signed out of RCU to test something and I couldn't get singed back in!!!
Imagine that!!! Me!!! the. The forum manager!!! I couldn't sign in!!!!! The two sign in's on a page are temporarily not working as our tech staff is working on a few things. But I did find that if I went to the home page of RCU and logged in there I was able to get in with no problems as all.
Give that a try and see if you can get in there.
Ken