i have the same problem and can't find the answer, hopefully this reply
may help us both get answers m8.
vista home premium, 2 gig ram, multiple hard drives.
i deleted the download manager using the add/remove programs as was instructed restarted and still it refuses to download flash
just had another look around and this works m8
i did get an error on installation about it not finding a file but when i ignored it it installed ok so i get to watch my iplayer again lol.
hope this helps you m8.