Help! My Laptop Keeps Showing Mailto Popups After Downloading Something

I can relate to the frustration! Have you checked your browser extensions? Sometimes an extension can cause weird behavior. Disable all extensions in Firefox and see if that stops the loop. If it does, re-enable them one by one to figure out which one is causing the issue.

If you’re getting mailto popups, you may need to check your default programs in Windows settings. Go to 'Apps' then 'Default apps' and make sure Firefox is set correctly for email links. If you’ve tried that and it hasn't worked, consider reinstalling Windows or restoring your system to an earlier point. I know it sounds drastic, but sometimes it’s the quickest way to get things back to normal.

It sounds like you might have picked up some malware while downloading. I recommend running a scan with Malwarebytes, including a rootkit scan, and doing a full scan with Windows Defender as well. If everything still seems messed up, you might want to post your situation in a malware removal forum for more specific help. For future downloads, it's a good idea to scan the links or files with tools like VirusTotal before opening them.