referenced memory issue

@Raj357610969hoe thats a tricky problem because the error itself is a generic system message, not a specific Adobe error code, meaning the root cause can vary significantly. Because you have don your due dilgence and gone through the steps as mentioned, there might be other issues at play. My first thought is not enough RAM, or faulty RAM... but maybe look at the following:

• Other applications, security software, or background processes could be interfering with how Acrobat accesses memory.

• While an Acrobat reinstall is thorough, underlying Windows system files that Acrobat relies on could still be corrupted.

• Faulty RAM modules, or even issues with disk drives (especially if virtual memory is involved), can lead to "memory could not be read" errors.

• Though less likely if it's happening with any PDF, certain complex or malformed PDFs could exacerbate a latent issue.

• These security features, designed to protect against malicious PDFs, can sometimes cause conflicts and memory errors.

• The first and simplest test is to completely disconnect from the VPN and, if possible, temporarily disable or exit the VPN client application. Then, try opening PDFs. If the error disappears, the VPN is almost certainly the culprit. 
• Some VPNs use their own DNS servers. Occasionally, conflicts with DNS resolution can cause issues. You could try temporarily switching your system's DNS settings to a public DNS like Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare (1.1.1.1 and 1.0.0.1) to see if that helps, both with and without the VPN active.

That's all I can think of that we do here in our department. Good luck!