Hmm... Just tested my own FLv3 Update, and it had no problem (not in and of itself indicative of very much).
Your error (as described in your most recent post) sounds just like the "someone has broken the DB" error, but that affects everyone when it happens; and the most recent DB change I am aware of is the countries changeover I made last weekend (the reason for this thread

So... back to diagnostic basics if I may. Have you run a FLv3 update before now that's worked, or is this your first attempt at updating after a first install? If it's not a brand new install, when did this error first appear (date if poss)? Has any other software changed in your setup in the same time frame, particularly firewall/anti-virus software? Equally, have you made any changes to your Internet Settings (in IE/Control Panel), these seem to be tied into so many other things in Windows since XP?