If it was just one or two shortcuts, the most likely explanation would be that the target file got moved, or its name changed. This would imply that maybe "a user" was shuffling things around.

Sadly, the most likely cause, if it was a bunch of icons and shortcuts, is probably an invasion by one of the "hijack" type slimes. The shortcuts are executed by one of those .dll thingies. I don't know offhand which one. A few types of "hijack" malware programs attempt to modify the "shortcut manager" so that you get their stuff when you click on a shortcut to something of your own. I'd have to do research to be sure, but I believe the same "shortcut manager" that works the links on your desktop also works web navigation links.

Some of the malware in circulation is quite "professional" and often works as intended by the vermin who distribute it. A lot of it is "amateur" cut and paste by idiots, and sometimes it just breaks things.

An "incomplete" removal by a "protection" utility can also leave a broken file or two, which may make your sytem "work different" or not work at all. Unfortunately, with the current rate of appearance of "new kinds" of crudware, no single program can manage them all.

This is just guessing, of course, based on your limited information. I know you've said you've got - and use - all the "protection goodies." They're generally pretty good, so it must be your "adventurous cruising" that exposes you.(?)... (just teasin')

It could also be that something in your setup could be adjusted. When you get it back from hospital, I'd suggest a visit to the Norton Security Check site to let them "probe" you and identify where you may have a hole or two. I've posted a link, and have it in my favorites, but will look it up later.

John