If this were just a few users, it might be something on their system. But you indicated many users are having issues.

Please post your website's address so we can check it out.

Here is the website URL: https://coinmastergen.com/

Please explain the problem in detail. What happens? What are the exact error message(s) ?

Are you seeing any kind of pattern?

Has the website been tested for malware?

Website is clean, there is no malware, I will try to find the pattern and get back to you.

Thank you again for taking time.

Disable the anti-tampering protection on the individual page or globally in the pages element of the web.config file using the enableViewStateMac attribute with a false value. I mention this purely for the sake of completeness - you should never do this on a production website.

   Manually generate a machine key and share that same value across each application (you could use the same key for all your applications, but it is sensible to use one key per application to maximise security), on each of your servers. To do this you need to generate keys (do not use any you may see in demos on the internet, this defeats the purpose of the unique machine key), this can be done programatically or in IIS manager (see http://www.codeproject.com/Articles/221889/How-to-Generate-Machine-Key-in-IIS7). Use the same machine key when deploying the website to all of your servers.