Hello, "freezes" are no crashes, so there won't be any crash reports. They often are generated by excessive CPU consumption. Does your TB also become unresponsive when you run it in "Troubleshoot Mode"? https://mzl.la/3AbU5jz

Hello, yes, it also becomes unresponsive even if in "Troubleshoot mode". In the meantime I was in touch with Microsoft support. They made a deep uninstallation and then a re-installation. TB seems to work now, but I am not able to import my profile folder.

The re-installation of Windows does it mean that you had to reinstall the Thunderbird application which created a new profile? Did you use IMAP or POP protocol for your email accounts? Did you make a backup of your Thunderbird profile folder before uninstalling Windows?

Hello, the installation of Windows was not changed. TB was uninstalled and then re-installed, creating a new profile. I made a copy of the old profile folder before that, but now I am not able to import the old profile using the TB import function. I am using POP3 email accounts. There must be some problem within the backup of the old profile....

So you created a new profile and set up your existing email addresses using the POP3 protocol. Am I right until now? Normally on termination of an account TB should have downloaded all messages still stored on the POP server. Please don't use the Thunderbird import feature. There is a safe way to do that manually but I need some more information about your backup of the profile. What kind of window do you see actually when you start TB? Can you tell me the name of the directory which contains your old profile data? Is it "Thunderbird" or "Profile" or somewhat like 1234abcd.default-release (or .default-esr)?