My site was hit by Panda

Hi,

we are running a Magento based online store with 15k products.
In January we did update the whole design, we did upgrade magento to the lates version and we added a mega menu navigation.

After 3 - 4 months our site just dropped in SERPS on all keywords and didn't stop until today....

I investigate this problem day after day but didn't find any issues, but today I did run a spider simulator and just find out what can be the main problem.
We do have about 250 categories and subcategories an all are listed in this drop down mega menu. All the categories are listed in menu, are visible in source and indexed by google
So every time google search any product on our page are there 250 + categories indexed on each page that I guess cause duplicate content and we did lose positions in SERP.

Is there any way to hide the navigation menu from Google spider?
Any Idea how?

Thanks

Not too familiar with magento cms but is seems like duplicate content is a common problem. Found somewhat recent read on it that will hopefully be helpful to you in trying to resolve this problem. searchenginejournal.com/5-duplicate-content-issues-for-magento/50640/

Let us know how you resolve that issue. Good thing about the filter is that once you resolve it, you should get back to similar positions you had previously.

Good luck!

Try to noindex the category pages. Use the canonical tag.

Use site:domain.com and see what pages are indexed, remove those pages that shouldn't be in the search engine.

Actually the problem are not pages, but problem it top navigation menu, that is indexed...
In this menu are 250 categories and subcategories listed and now on all product pages is Duplicate content with 250 categories

Did you ever resolve this?? I don't use Magneto, but I have what I believe is a similiar problem with my Table of Contents causing a panda slap.