Hi,
First things first, the page, http://www.thinkdigit.com/top-products/Ultrabooks/top-10-ultrabooks-153.php is not in Google's index.
Secondly, for both the phrases, 'top 10 laptops' and 'top 10 ultrabooks', the page,
http://www.thinkdigit.com/top-products/Ultrabooks/top-10-ultrabooks-153.php, ranks in the first position from your website, thinkdigit.com
So when you try to look-up the cache for a non-existing page in the index, Google tries to return the closest match and which is, http://www.thinkdigit.com/top-products/Ultrabooks/top-10-ultrabooks-153.php
I see a problem with the Sitemap.xml file for your site. Its not comprehensive and if you look at the cache of it in Google, you will see, the page, http://www.thinkdigit.com/top-products/Laptops-and-PCs/top-10-laptops-124.php is in there but its missing in the current Sitemap.xml file.
Here are three things you might do to make http://www.thinkdigit.com/top-products/Laptops-and-PCs/top-10-laptops-124.php in to the Google's index.
1. From Google webmaster tools account, Fetch as Google the above page and submit.
2. Come up with a comprehensive Sitemap.xml file
3. There is no reference to the Sitemap.xml file from Robots.txt file. You can add it as follows:
Sitemap: http://www.thinkdigit.com/sitemap.xml
You should be good after that. All the best to you my friend.
Regards,
Devanur Rafi