Assassins Creed weird problem

I was playing perfectly fine until the memory block 3 where the game freeze for like 5 seconds and goes back to normal whenever i kill or assassinate any target or person , or jumping and falling freeze the game for 5 seconds too, then it will goes back to normal.
I was running bittorrent, msn messenger, firefox background all the time, the game runs perfectly until memory block 3 where the freeze begins, and i found out if i disconnect from the internet, the game runs perfectly without any problems at all, but if i connects back, the freezes come again...help plss

My specs
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E7200 @ 3.16GHz at 1.264v in CPUz ; VID 1.2250 ; 50~53c full load ; 31~34c ambient
2X2GB Corsair DD2 800 XMS2
Asus P5N-D bios ver 801
9600GT 512MB/256bit
iBurst USB Modem
80GB Seagate HDD

I've played the whole game couple of time before with 9600GSO on XP and Vista and had no problems. Most likely some windows setting can fix it, but don't know how...

I know the problem you guys are having, its occuring when you kill an enemy or even when its coming to a save point the game starts freezing right? well I bought this game off steam last week and had this problem occuring to me as well, I'm currently at work so I dont have the actual link, but if you look up steam forums and find Assassin's Creed game forum you will come across alot of other users having similar problems their is a topic their that can provide a solution for you guys.

P.S : I actually found the link for the forum, this should have various threads and solutions for helping you fix this problem guys, hope this is helpful.

Link: http://forums.steampowered.com/for [...] .php?f=381

It seems the Ubi's servers are up again - i'm not getting any more freezes for few days now