I was working on a very low spec laptop last night and I had disabled Kaspersky Internet Security 7.0 a day or two before. As I was just working on this site using Firefox I felt pretty safe in doing this and it helped the laptop's speed a lot.
Anyway, I was trying to look at the site in IE and it would not load last night. I figured it was the DNS change over causing it to throw an error. Just the generic "Internet Explorer cannot display this webpage" - so, as it was late, I called it a night.
Get up this morning and same centering error in firefox and IE cannot load the site. IE was to the front so I thought I'd Google a bit. A-ha... Google won't load either.
Switched Kaspersky back on and it warned about IE having been recently updated. Told it to Allow the new version access to the network and loaded the site.
All aligned left. Tried in Firefox, all aligned left.
Shutdown Kaspersky, IE loads the site and aligns Left. Firefox loads the site and aligns centre.
IE and Firefox both latest versions (not beta 3 of FF) - very wierd.