really large hidden update?

yesterday there was an update of 450mb and today i got a new update of 36mb

There has been a lot of updates over the past few days. Using GODh's figures, it's possible you downloaded only 190MB of yesterdays, and then the remaining 240MB + 36MB from today.

There was a huge 20 thousand file update (not a mandatory one. It is one of them that downloads when you play) that came after the nightfall screen changed.

You could just use -image and wait for that to download. Then you won't have to worry about it downloading while you play, if that helps at all....

If you had bothered to look at the Guild Wars Update page you'd see an explanation.
http://www.guildwars.com/support/gameupdates/

Pay particular attention to the line mentioning preparations for the Nightfall preview event.

hmmm didnt mention anything about making it near impossible to find a gold chest ive opened about 30 chest now all purple since the last update dont see the point in wasting money on keys now if thats the case

Must be just you. I've gotten 9/15 gold chests today.

i must have the curse then. ive also been to fow 3 times and not 1 shard for me.. oh and still no gold chest from 35