How are you doing this? What version of Thunderbird do you have?

I have this same problem. The email message window freezes when I hit CTRL + k or Insert -> link. I'm using Thunderbird version 140.1.1esr. Thanks

@Scott, you might have a similar problem or not. In your brief one and a half lines you identified inserting hyperlinks specifically resulting it a freeze. That is nothing even vaguely similar to the original assertion here

Cannot insert clipart nor hyperlinks into email

Is this because the poster does not know how to actually do it? Or something else.

Nothing is clear about what the problem is here. Other than the original poster is struggling to add clipart and hyperlinks for some reason. You apparently are also struggling for some reason which you think for reasons that escape me is the same thing.

I suggest you post your own question asking for assistance with your problem and devote just a little time to explaining the issue clearly. Does it happen in Thunderbird troubleshooting mode for instance? My immediate guess without any substantive information is you have an issue with an antivirus product inspecting links before they are inserted. Troubleshooting mode might shed some light. It might also be you use an operating system that limits your ability to undertake certain functions. I am seeing more and more of this from Linux and Apple users for instance but I would not exclude Microsoft as totally benign in this sort of thing either. You have what may be a complex issue and your simplistic "I can't and someone else can't" view of it will not help in determining a cause or a cure. Your issues may be similar, or they many be about as similar as one who can not start their car because they have lost the key and another that can not start the car because it has no motor. Neither start.

There isn't a dedicated "Clip art" gallery feature in Thunderbird like you might find in Microsoft Office programs. Thunderbird focuses on providing a robust and customizable email client, and its image insertion works differently: Composing in HTML format: Ensure your email composition is set to HTML format to enable image insertion. Insert Image option: Use the "Insert Image" option in the compose window to embed images from your local files or a web URL. Steps to insert images in Thunderbird Open a new email and click in the message body where you want the image. Select Insert > Image from the menu. Choose "Choose File" and locate the image on your computer, or provide a web URL if the image is hosted online. Consider adding alternate text for accessibility and in case the image doesn't display. Ensure "Attach this image to the message" is selected for embedded images, according to a Mozilla Support forum. Click "OK" to insert the image. You can also drag and drop image files directly into the compose window to insert them. Important considerations HTML format: Ensure your message is composed in HTML for the best results when inserting images. Image location: If you use an online image, make sure it's accessible and won't be removed, warns Email Signature Rescue. Large images: Large image files can increase email size and potentially cause display issues. Optimize images for web use by reducing their file size before inserting them. Recipient's email client settings: Some email clients may block remote images (those hosted online and not embedded in the email) for security reasons. You can adjust this setting in Thunderbird's preferences.

You might want to check your email settings or client. Some email services block clipart or hyperlinks for security reasons. Try using a different format (like plain text or HTML) or make sure your email client is up-to-date. If it’s a corporate email, there might be restrictions set by IT.