Since the tech guys are out of the office, and we're at least one experienced helper short, I'll offer a couple of ideas.
First, I've found a problem in XP in that downloads and installations need to be done with Administrator privileges enabled or they don't seem to install properly. I don't know the setup you've got under Vista, but it's worth mentioning that just in case. The message "You may not have the appropriate permissions" seems to imply two different levels of privilege available to your OS.
Second, the blank icon means that Windows knows there's meant to be something there, which perhaps means there's a discrepancy between the locations stored in the registry and the actual locations of the files. However, you say the icons show up in Safe Mode, so that may not be the reason.
The tech guys would have asked you to do a scan anyway in Safe Mode, because I do know that something working in Safe Mode but not under normal operating conditions is sometimes a clue that malware is present on a machine and has interfered with the AV software settings to prevent its detection.
You might want to try using Microsoft's own scanner, which is in the Live Onecare area of their website. You could go to http://onecare.live.com/site/en-gb/center/whatsnew.htm for a Vista download; there are instructions there on what to do if you're using Firefox - note that if you're in the US there's probably a different URL for a more local server. While you're at it, let the scanners clean up your disk and registry and do a defrag as well. The whole process takes a while, but if you suspect your McAfee installation might be compromised it's a useful tool to have available.
Finally, it's always a good idea to scan for problems with one of the other programs that everyone should have lying around just in case - Malwarebytes Anti-Malware and/or Spybot. There are some others but I haven't got around to testing them yet so I can't say how good they are.
That's just for starters. It'll save you a bit of time when the tech guys get on the case. They'll also want to know which versions of McAfee products you've got, and may advise you to uninstall and reinstall McAfee in case the upgrade was somehow botched - but that's second-guessing, I'd better let them work through their own checklists.