I de-installed their anti-virus system using their recommended procedure as the pre-installed free trial period was about to expire. But it left behind some nasty stuff that protected me very thoroughly. Protecting me from being able to use FTP, or to use a new version of a browser, for example. For my own good, of course.
Because FTP was disabled, I couldn't access Norton's special removal tool to get rid of the cruft, as that had to be downloaded by, you guessed it, FTP.
Good that they provided such a thing, bad that the problem is so common that they had to. Very bad that they've known about the problem for ages, they just haven't bothered fixing it.
So manual surgery was needed on C:\windows\system32\drivers\. The first attempt disabled my Internet connection completely. I eventually got it working though, 6 hours of my time wasted on a piece of used food. But in the process of re-installing Firefox, I lost all my bookmarks, user names, cookies and passwords.
The picture is of Hallucigenia, an extinct animal of the Middle Cambrian. But I prefer to think of it as a Pet Hate.