Unable to edit or update pages after migration

I am migrating a wordpress site from one server to another but keeping the same domain.

I FTPed the files to the new server, and initially everything was working fine, except a few of the visual/layout components were off. I use headway, and it looked like some of the files may not have transferred completely.

I could get into the admin panel work from there, but I wanted to try for a complete migration instead of redoing a portion of the layout.

I downloaded the files again and then uploaded this more recent set of files to the new server, and suddenly I could not do any work from the admin panel. I could log in and see it, but I cannot update or publish any pages. I also can’t import, etc– anything that involves a change to the site via the admin dashboard.

I began making some layout changes through the visual editor, a feature of Headway (as the layout problem had also not been fixed,) and I was able to save those changes. After the first change, some of my fonts and colors went back to the “default” setting (also don’t know why). I have been able to restore those as well, manually. I’m in the middle of that process now.

What is going on here, and most importantly, how do I fix it?

I have until Monday (7/30/2012) to fix this before the migrated site goes live. Right now it’s at https://www.tripudiamos.com/tangonyc/ And I did check that the wp-config file had the right settings.

Thanks for your help!