Pages with duplicate title tags

My client site had ranks No1 for 4 keywords, then disappears. When I am checking rankings for these 4 keywords, I cant find my homepage in google. But can see inner pages. Site is still indexed and have PR.

Just check webmaster tools and find this:

1. Pages with duplicate title tags 2 (webmaster tools find duplicate title tags)

And I find 2 mails:

1. Dear site owner or webmaster of mysite. com,

As of the last crawl of your website, you appear to be running WordPress 3.2. Google recommends that you update to the latest release. Older or unpatched software may be vulnerable to hacking or malware that can hurt your users. To download the latest release, visit the WordPress download page. If you have already updated to the latest version of WordPress, please disregard this message.

If you have any additional questions about why you are receiving this message, Google has provided more background information in a blog post about this subject.

Best wishes,

Google Search Quality Team

2. Dear site owner or webmaster of mysite . com

Your site appears to be running an older version of WordPress. Google recommends that you update to the latest release. Older or unpatched software may be vulnerable to hacking or malware that can hurt your users. To download the latest release, visit the WordPress download page.

If you have any additional questions about why you are receiving this message, Google has provided more background information in a blog post about this subject.

Best wishes,

Google Search Quality Team

What you think? This is problem with my site: duplicate title tags? When I fix this all, site will back?

Thx
Amy