"Error getting file security" when downloading iTunes

I have been ignoring this for sometime but just bought myself a nano and need the latest itunes in order to use it. Please help. Someone already had this problem in 2009 but there was no solution posted...

C:/ProgramData/Apple/InstallerCache/AppleSoftwareUpdate2.1.1.116/GetLastError:5

There's a 'solution' here: https://discussions.apple.com/thread...1764&tstart=15

I take no responsibility for any problems the 'solution' may cause as I haven't tried it out myself as I haven't had the problem.
Good luck with it though :)