Please test to see if your Anti-virus/firewall program is causing this.

In the Anti-virus/firewall program Switch off scanning emails.

Thunderbird automatically does not allow remote content to show. Any attachments you open should still be scanned.

Hi Toad-Hall,

I'm using Microsoft Security Essentials as my anti-virus software on Windows 7. I turned the "Real-Time Protections" function to Off (using your recommendation). After that, my Thunderbird was working again (38.3.0) version. Then, I went back and turned on the "Real-Time Protections" to On and when I went to Thunderbird again, it continued to work.

Thanks for your help.

Hi Toad-Hall,

When I logged back into Thunderbird today with the Microsoft Security Essentials "Real-Time Protections" function turned back on, I got the same error messages as before "Thunderbird Not Responding". Then, when I turned off the feature again, Thunderbird was working. So, it appears that the anti-virus software is the issue. This problem happened only after Thunderbird 38.3.0 was updated on my computer. So, I can report the problem to Microsoft although I haven't seen this problem posted on any forums.

I contacted Microsoft support and they said this is a Thunderbird issue.

It is and always will be a Microsoft issue. I had exactly the same issue with MSE and Thunderbird back in the days of Thunderbird 3. I dumped the Microsoft junk and have not looked back.

There are many free anti virus alternatives to MSE. Almost all of them offer more functionality and better hit rates when catching bugs

re :I contacted Microsoft support and they said this is a Thunderbird issue.

I'm not surprised by their comment, but Thunderbird is not doing the scanning. Thunderbird cannot be reponsible for their product. It is the job of any anti-virus product to work with whatever it claims, not the other way around.

googling will produce loads of issues with MSE slowing down PC.

I've had a thought, is Thunderbird one of your auto 'Startup' applications? I located a link to some info on stopping MSE scanning Thunderbird on Startup.

• http://yourbusiness.azcentral.com/remove-startup-programs-microsoft-security-essentials-21789.html

1) I found that Thunderbird was not one of my auto Startup applications, as Toad-Hall suggested to circumvent if it was on auto-startup.

2) I removed MSE and installed another anti-virus software (Bitdefender) and now (as of 1 day ago), Thunderbird is working fine.