mybigfatmouth18 on "Internal server error AND New user registration"

I'm getting all these new user registrations from spam emails AND this internal server message, every other time I click on ANYTHING.. PLEASE HELP. I have not been able to do anything for a week on my site..

SAMPLE : Im getting emails like this:
Internal server error AND New user registration
Username: mxkdjbff
E-mail: jk.x.lo.p.iy.x.a.h8y.kqcbnm@gmail.com