Have to login twice

One of my testers noticed that they have to log in twice to actually get logged on tot he site.

I installed registration magic to get the remember me checkbox.

If I go to the logon screen ([profilegrid_login]), my User name and password are automatically filled in by my password manager, I check remember me, then press Login. The screen flickers, then I’m back to the blank login screen.

It always seems to work the second time following the identical procedure.