i had this EXACT same problem. i upgraded my vbulletin from 2.x.x to 3.0.7 and Photopost from 4.8 to 5.0.3. i kept getting that crazy "Invalid login" problem. here's the only thing that seemed to work for me.
in phpmyadmin, in the settings table, check id #41. that's the vbversion varname. it probably says vb2. edit it to say vb3. that's what worked for me. hope that helped.
edit: oops, i saw pictures and no table formatting. so just a reminder that you might want to set to integrated vb3 forums. this is under Forum Settings.
For everyone getting this problem, i hope this helps somewhat.
Last edited by jetrome; April 5th, 2005 at 03:27 AM.