Strange Redirection Problem

I don’t know what’s going on.

Yesterday who entire website kept redirecting to - that’s exactly where it was going.

Now, it’s back to normal except for the /blog/ subdirectory still redirects to ONLY if there is a www. in front of it.

If I just http://…/blog/ it works.

But if I http://www.//…/blog/ it goes to www.somedomain.comblog/

Any suggestions would be appreciated.