Actually there's also the distinct possibility that BitDefender is the culprit, trying to follow that path as well, see where the solution will come from.
I'm running 32-bit Vista Home Premium SP2 and yesterday I checked for updates and saw 3 released apparently outside the regular schedule, 2 security updates for .NET Framework 3.5 SP1 (KB2416473 and KB2416470) and one dealing with time zones (KB2158563). I can probably rule out the last one as the culprit and assume the first 2 deal with the .NET vulnerability that I've seen mentioned lately. Also assume they, or one of them, are the culprits.
What happened after installing them and rebooting (it didn't ask for reboot, but I did anyway) was that my antivirus (BitDefender Internet Security 2011) was saying that there are "multiple problems" if I hovered over the taskbar icon, but when I opened it it said there were no problems. Scratched my head about that, but more or less assumed it was a scare tactic because I just have 4 days left on the license.
That was until just a bit ago, when I tried to see processes from all users in task managed and nothing happened. Rebooted, tried again, still nothing. Then meant to open command prompt as administrator and try another approach, only for it to say that it can't access the file and that perhaps I don't have the correct privileges.
cmd.exe and consent.exe exist in system32, checked that.