Here is a message I got from own of the sites I am having problems with...
Thank you for contacting Nick Arcade.
The error message you received is generated when your game is unable to
contact our registration server to verify your purchase.
Ad-blocking software, home firewalls, or other security software
(Norton, ZoneAlarm, etc.) may affect your ability to register your game.
Temporarily disable any ad-blockers or firewalls you have running.
If you use Windows Vista, Microsoft has included new security features
not previously found in other versions of their Operating Systems. These
features may prevent you from downloading,installing or registering
content from web sites, including NickArcade.
Please refer to the built-in help section of Vista to learn more about
its new security features.
You may also wish to refer to Microsoft's support page found here:
http://www.microsoft.com/en/us/default.aspxTo unlock your game, enter the email address and password you provided
at time of purchase. This information can be found in the confirmation
email you received at the time you purchased your game. Once you enter
your email address and password, the full version of the purchased game
will unlock.
To avoid errors when entering your email address and password, the best
thing to do is copy and paste it directly into the activation field.
To copy: Use your mouse to select your email address or password, then
press the Ctrl and C keys simultaneously.
To paste: Click in the box where the email address or password is to be
entered, then press the Ctrl and V keys simultaneously.
IMPORTANT:
*If your email address contains a mix of lower-case and upper-case
letters, try entering your email address in all lower-case letters.
*You must be connected to the Internet before attempting to unlock your
game.
*Temporarily disable any personal firewalls or antivirus software that
will block you from connecting to our key servers.
Please let us know if you need any further assistance.
Regards,
Nick Arcade Customer Support
This still does not work 
