Did you move the site from being a root web site to a virtual directory or move it from one machine to another?
Is it running on apache?
Assuming this is the relevant error (and I'm not sure it is)
I would look at are the mp_Pages table. I would look for the row with the url indicated in your error:
"Could not find the sitemap node with URL 'http://www.secontainer.com/'" and maybe remove that url
It might also be worth reviewing the mp_FriendlyUrls table and look for incorrect urls.
It would be best to clear the log, then visit your /Secure/Login.aspx and then immediately see what got logged.
Hope it helps,
Joe