Are you referring to the login box in the upper right hand corner of the web page or the login box at the bottom of the web page?
I've noticed the problem with the upper right hand corner myself... not quite sure why you can't alt-tab to the next field.
You can alt-tab between the fields at the bottom of the web page. I'll try to look at the code in the SMF theme, perhaps there's a problem with it.
Cheers!
PS: I think your avatar got broken in the server migration... you might want to re-upload it again, sorry.
