Guess what, I recently upgraded to 3.2.1, recently is about 3-4 days ago.
I remember of logging in to the dashboard because I did the network update (about 30 sites).
But now when I try to enter in each of the site dashboard, I get 404.
On some sites there is a redirect loop also on /wp-admin/ with a login=some-numbers-and-letters&k=letters&k=timestamp
The sysadmin of the server also told me that ms-files.php is causing a lot of errors:
Premature end of script headers: ms-files.php, referer:
I do have a backup but at this time it would be preferably fix the issue, if anyone could share ideas on how to fixing this I'd appreciate.