What is the worst experience you have ever had involving Viruses/Malware?

Only virus I ever got was pespaces back in the 95 days it was a hard mess to clean up mainly because it infected every single exe file and broke a lot of them.

Kinda remember cleaning it up from a dos floppy then once clean basically reinstalling every broken program one at a time.

In hindsight I should have just done a fresh install but I was new to computers.