What is your anti-virus software?

What is your anti-virus software?

Anti-virus and anti-malware = built-in Microsoft Security Essentials; Anti-malware = Spybot and CCleaner

(I should mention that I never had this problem while using previous Thunderbird versions, for many years -- and I haven't changed anti-virus or anti-malware programs since moving to this newest Tbird version.)

Try to start Windows 7 in safe mode with networking enabled.

Still in Windows safe mode, start Thunderbird in safe mode. Does the problem go away?

Windows safe mode disables anti-virus software. This is a troubleshooting step, not a solution.

Thanks, christ1.

I'm not sure that trying Windows 7 in safe mode will be viable for me: the freezing can take 24 hours to occur, and I don't know if the programs that I normally use (midi, digital audio, graphic design, etc) will function in safe mode. Similarly, while I don't mind shutting down my anti-virus software for a short test, I would worry about leaving my computer exposed, without anti-virus protection, for 24 hours. Please correct me if I'm wrong about this.

I don't know if the programs that I normally use (midi, digital audio, graphic design, etc) will function in safe mode.

Then give it a try.

I don't mind shutting down my anti-virus software for a short test, I would worry about leaving my computer exposed, without anti-virus protection, for 24 hours.

I think while running an outdated OS, which doesn't receive any security updates anymore, turning off anti-virus s/w for 24 hrs is the last thing you'd have to worry about. I'm not even sure whether Security Essentials for Windows 7 still receive definition updates. Running two anti-virus on-access scanners simultaneously is asking for trouble. If this is what you're doing, first thing I'd do is to get rid of one of them.

As said before, Windows safe mode is a test, not the solution.

Thanks, christ1 - I'll try it.