Norton Family not working/can't be uninstalled

I am running Norton family on several computers.  One of them is a very old PC running Windows XP (which works perfectly).  It worked fine for several months but then, a while ago, Norton Family suddenly stopped monitoring activity on that computer (it says that it is still running, but is not monitoring anything; it is working fine on the other devices).  No matter what I do, I cannot get it to work, and also cannot uninstall it (in order to reinstall afterwards) - when I try to uninstall, it says "connecting with the Norton Server" and then hangs there endlessly.

What should I do?