Unidentified 404 not found pages

Question

We are getting lot of 404 page not found error which we can't find the reason with same pattern. We are not doing any redirect for this 404 pages or we are not giving link anywhere for this broken page links.

The common point for this errors is partly manipulated with same pattern; removing first segment of URL's. Example;

This is true URL's;

site.com/category/news/title-of-the-content

site.com/another-category/news/another-title-of-the-content

...

This is what we getting 404;

site.com/category/news/

site.com/another-category/news/

...

We are collection user agents for 404 errors, and here they are;

Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)

Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.2; WOW64; Trident/6.0; .NET4.0E; .NET4.0C; .NET CLR 3.5.30729; .NET CLR 2.0.50727; .NET CLR 3.0.30729; InfoPath.2)

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; InfoPath.2; .NET4.0C; .NET4.0E)

So this error only occurs in Internet Explorer.

We think this happens because of some IE plugins but can't find. Anyone have same problem? Or what we can do about this situation?

Thanks in advance.

Bonus:

Answer 1

It could have something to do with users using 'safe mode' from their browsers. This link shows how the Mozilla Support addressed a similar situation https://support.mozilla.org/en-US/questions/1003468