Yes, the same problem for me with Ceska rep. NT. Click on Set Lineup in schedule page ends this way:
Oops!
Something went wrong with your request. The error has automatically been logged and reported to BuzzerBeater developers. Some errors go away when you hit the back button and try again. If you continue to get an error, you can post about it in the bugs forum.
On the new site, the most common reason for this error is because you were trying to access a page that assumed you were logged in when in fact you were not (probably becuase your session timed out). So simply logging in and trying again might solve your problem. We are working on fixing this more elegantly.