Upgrading Drupal

Newbie here,

upgraded from 6.17 to 6.20 and in the status report the only error i get is "There is a security update available for your version of Drupal. To ensure the security of your server, you should update immediately! See the available updates page for more information."
In the status report it says my version is 6.20.
IN available updates it says drupal core 6.17.
Available updates recommended- 6.20
then below it says security update 6.18

What it going on? how can i fix this? and thanks in advance.

Followed all the instructions upgradaing 6.19 to 6.20.
Everything still works as before, but the status report still reports 6.19 as installed?

Yes - I ran update.php after copying files over, cleared cache. I'm a Drunooobie..

Any ideas?

--updates--
1. It appears I did not ftp the 6.20 files to the root site folder as CHANGELOG.txt still had 6.19 version. Copied all files over, ran update.php - still no happiness.

Summary: After upgrading Drupal to 6.20, my attempts to run update.php failed. The system displayed Drupal's "page not found" page.

Solution: The permissions on update.php should not allow group write. The permissions were 0664. They should be 0644.

I have been trying to test out the transfer of an established Drupal run site to another url hosted by godaddy. My plan is to get my test url to mirror the site I have, then to give it some badly needed updates. After I've gotten my test url fully functioning, then I'm going to actually move the established url to godaddy (or another hosting company if I need to), and repeat the process quickly and efficiently.

Problem is that I can't seem to get the test site up and running. These are the steps that I've taken:

1. Copied all files from established site.

2. Used FTP to place all of the copied files into the new test url.

3. Exported the MySQL DataBase (in several pieces) and saved them to my computer.

4. Imported all of the SQL files to my newly setup database.
Here I made sure to only export and import the emptied cache tables

5. Edited the public_html/sites/default/settings.php file by placing the applicable information.

$db_url = 'mysql://username:password@localhost/databasename';
$base_url = 'http://www.example.com';

6 I had read something about disabling clean urls, so I placed this at the bottom of settings.php.

$conf['clean_url'] = 0;

By going to www.example.com/public_html/index.php I can access the index page, but it doesn't show any of the css styles that it should. Also none of the links go anywhere.

I upgraded a multi-site setup. All appeared to go smoothly...more or less. I signed on to each site using the superadmin id's and passwords, still all good.

After signing out of every site, I cannot get back in. The userid and password is showing as unrecognized. When I hit the "change password" button, I get an e-mail that looks like this:

!username,

A request to reset the password for your account has been made at !site.

You may now log in to !uri_brief by clicking on this link or copying and
pasting it in your browser:

!login_url

Our Drupal site is broken to the point where we can no longer login (when we try we get a blank screen). I believe our ISP upgraded something else on the server to cause this problem, because as far as I know nothing else has changed. Aside from user added content, nothing has been updated on the admin side since January, 2007.
The version information on the server is as follows:
Drupal version: 5.1
Apache version: 2.2.17
PHP version: 5.3.4
MySQL version: 5.0.91-community