Here is an awesome post which gives solution to solve some of the common technical SEO problems.
1. Uppercase vs Lowercase URLs
2. Multiple versions of the homepage
3. Query parameters added to the end of URLs
4. Soft 404 errors
5. 302 redirects instead of 301 redirects
6. Broken/Outdated sitemaps
7. Ordering your robots.txt file wrong
8. Invisible character in robots.txt
9. Google crawling base64 URLs
10. Misconfigured servers
Read more for the solutions of these problems http://www.seomoz.org/blog/common-techn ... solve-them