it happen to me too, but in a different mode.
my error was (i solved and i will tell you how to fix): an error occurred while trying to replace the existing file: delete file failed: code 5
it seems it was a problem with 7zip.dll
i've tryed with a ccleaner, reistalling 7zip codec, scan disk and defrag but none of them works.
then, i figure it out it was the anti virus; wh keep all the unknow files in the sand box.
just turn off your AV for the first installer and everything will be fine.
plz vote up if it was usefull (green arrow). here
regards
