Checking htaccess files
If your site is redirecting to another site, and shouldn't be, an htaccess
file may have been injected with corrupt code. Take a peek for rewrite directives to suspect URLs.
While you're about it, you should also be on the lookout for cloaking, where search engine bots are directed to third party sites. A typical scam looks like this:
RewriteBase / RewriteCond %{HTTP_USER_AGENT} (Googlebot|MSNBOT|Slurp) RewriteRule ^ http://somescrapersite.com/ [R=301,L]
Sometimes code is added way down the page, after many blank lines, so be sure to check right to the bottom of your htaccess
files.