Login problems

I have just recently upgraded from an old version to the
latest joey version of campsite. Our subscribers use the
email address as a username to logon.
Something within campsite does not like a username either as
long - or containing an  char.

I keep getting 'Invalid Username' message. I have tried
with a completely new login template created using the Login
tags etc. 

However, when signing in with a 'normal' user name all
works ok.

Anyhelp appreciated as I am stuck at this point.

Patrick