Missing command line parameter -prodid

So, my AC2 wont start at all.
It goes to the steam launcher, and instantly pops up the message:
"AssassinsCreedIIgame.exe has stopped working"
What's up with this?
Well, since the problem seemed to be with the launcher, I went to Steam>Steamapps>Common>AssassinsCreedII>Redist>Gam eLauncher
and installed it. When I tried to run it, It said:
"Missing command line parameter -prodid, see the integration guide for more details"
Anyone else having this problem?
Solutions?
Ideas?

[kick_my_a**247]

yer same prob with splinter cell convictions
no answers yet

[dyabel]

check your ports - firewall
try to run AC as Administrator

[Shinbusho]

64bit OS Instructions:

1.) Click Start
2.) Type 'regedit' (Without quotes) in search bar.
3.) Click/(Press Enter) the regedit.exe option that appears at the top under programs(1)
4.) If you get an options box appear with a yes/no option - click yes.
5.) In the folder structure on the left: Look for HKEY_LOCAL_MACHINE and double click it to expand it
6.) Under that look for SOFTWARE and double click it to expand it
7.) Under that look for Ubisoft , right click it and choose export.
8.) In the save dialog, click desktop on the left, and type something in the filename box.
9.) Close all windows

10.)Find the file you just saved to your desktop, right click on it and choose edit.
This should open the text file in notepad.

Carefully go through the file, and everywhere you find
[HKEY_LOCAL_MACHINE\SOFTWARE\Ubisoft
change it to say
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Ubisoft
In mine, there were 6 places to change - I expect this will be the same.
Save the modified file and close notepad.
Double click the file on your desktop and say yes to everything that follows.

If you get this right - you should now be able to run the game.

What about a 32 bit processor?