Weird bugs on D7

My site has been working well as I have been setting it up. Then, today, after I made some changes to my email templates, 2 weird things are happening:

1. I get an error page whenever I click to view a profile.

2. In Admin, I can't open the language settings page. Every time I try I'm prompted to sign in admin again but won't accept my password. I have to enter admin via my homepage (which still knows I'm logged on). All of the other pages in Admin seem to work but not language settings.

Can any one help?

1. What is the error that you are receiving?

2. The answer to 1 could be the solution to 2.

I get the following message:

404 Not Found

The requested URL ....was not found on this server.

Additionally, a 404 Not Found error was encountered when trying to use an ErrorDocument to handle the request.

I re-installed D7 and re-loaded my backed-up DB and all is working well it seems.

Thanks MRFenix for your help.

CORRECTION: When I go into Forums I get the following error message:

Warning: curl_setopt() [function.curl-setopt]: CURLOPT_FOLLOWLOCATION cannot be activated when in safe_mode or an open_basedir is set in /home/thehous1/public_html/inc/utils.inc.php on line 895

Any ideas?

The "CURLOPT_FOLLOWLOCATION" means that your website host does not allow "open_basedir" In otherwords, ask your host to enable "open_basedir" and hopefully they can make that change for you.