Windows XP SP 3
The system is a new installation.
I have downloaded the trial version of DW and I am receiving the following
error message:

A problem was encountered while trying to load the trial period for Adobe
Dreamweaver CS3.
Click Quit to see if restarting your computer or reinstalling the software
fixes the problem. Otherwise click Continue to display a screen where you can
enter a valid serial number to begin using the product without trial.

Why nobody answer me?
I have formatted the PC for other reason and now the problem is the same.
I can't try the program it will ask me only a serial number...

The only recommendation I can make is to run the CS3 Clean tool and try
re-installation.

http://www.adobe.com/support/contact/cs3clean.html

If there are error messages thought you should consider trying to contact
Adobe support if they continue.

Since this is a USER TO USER forum, not Adobe support, and as the
only way another user could reply is if they had that EXACT problem
and also had a solution, you may need to contact Adobe for help

In the US - Adobe General support 800-833-6687
In the US - Adobe Install Problems 800-642-3623