There are several threads describing this problem, but let me summarize what I've found, and my experience with Symantec chat support.
First, the original problem: on my wife's XP Pro SP3 system, there was a nag pop-up describing the free upgrade to NAV 2009, so I told her I'd take care of it. During the installation, it uninstalls the prior version, and eventually reboots. After rebooting, all desktop icons (except a few "system" icons like My Computer, etc.) and start menu items were displaying as "programName.LNK", and the links were broken. They can be repaired - individually - by browsing for the appropriate EXE when prompted by Windows, but this is clearly unacceptable.
I then accessed Symantec Chat support. In the course of multiple chat sessions across 11 hours, the system is now worse off than before, in fact, it is totally unusable. Also, I was told by multiple agents that this problem had not been reported before. Apparently, they don't monitor these forums. They don't read the transcripts of prior sessions either, because I kept having to explain the same things over and over again.
The initial chat session was, necessarily, from a different computer than the one that had the problem. In the course of that session I described the problem and ran back and forth getting information. The agent suggested I reboot to the last known good config, but that was in the same state, so it became clear that the problem, if in the registry, was not in the control sets.
I then suggested using System restore, which the agent said was worth a try. Of course, I could not run it from the start menu, but there's another route: reboot to Safe Mode, and then after you log in, click "No" when you get the Safe Mode confirmation dialog.
So I selected a system checkpoint from earlier that morning, and after rebooting, all my LNKs were restored. So far, so good.
I described all this in the next chat session, and was given a 30-day credit and a link to the current NRT, and to an installer that would reinstall NAV 2008. I downloaded those and copied them to a share on the other machine. When I ran NRT, guess what? All the LNKs were broken again after it rebooted. No only that, it didn't look like it had actually removed anything.
So... I repeated System Restore, and went back for another chat (it was now 4 hours into the repair process, and I dozed off while waiting in the queue).
This morning I got on chat again, this time on the machine that had the problem. I described everything that had occurred, and the agent decided to try Remote Control. I had described the NRT issue, and when I saw he was preparing to run it, tried to get into the remote session dialog to send him a message, but he kept minimizing the dialog! In any case I couldn't get the message in, and he ran NRT anyway. After the reboot, all the LNKs were gone, and of course the remote tool wouldn't run so the session was lost.
I did another System restore and went back to chat. This time, the case was escalated after a few minutes. The case manager also wanted to use remote control, and use NRT, and I warned him about what had already happened. He also wanted to boot to Safe Mode, where he deleted all Norton or Symantec folders, and used regedit to delete all related keys from the registry. Remember, I'd warned him about NRT? Well, when he rebooted after all that, the LNKs were broken again, and the session was gone.
No problem, right? I'll just do yet another System Restore. Except that now, all the restore points are gone!
The next chat - back on this computer again - was also escalated. The case manager reviewed the transcripts, and insisted the other case manager had not deleted the restore points. That may be true - or at least, he may not have done it on purpose. But the fact remains that after his activities in Safe Mode, they were gone, and I could no longer restore the system.
The case manager refused to admit responsibility for this. In fact, I kept getting the same "I'm sorry that you're having this problem." response, which I suspect is a keystroke macro - boilerplate from the legal department.
I will try individually re-adding file associations for EXE and LNK as described in the other thread, but I suspect the associations are also gone for all "executable" filetypes such as CMD, BAT, etc., so this is a partial and unacceptable workaround. I will probably have to wipe the machine and reinstall.
So, my wife will lose time on her projects, and I'll have to devote otherwise billable hours to fix her machine. Apparently, Symantec views that as an "acceptable resolution". In the past, I've defended Symantec products. But after this experience, I'm considering making a switch.