Hi. Sorry I haven't been on in a while and I just saw your questions. What kind of problems are you having? Which operating system.
I'll assume you are running XP. Are you using the lastest drivers? I was about to point you at the FTP site, but I see now that they are requiring a login. What is up with that?
I too have a 766, and when I start seeing some flakeyness, I reseat the ram and it goes away. With the power off, a/c adapter disconnected and battery removed, lift the keyboard and set it over the touchpad area, then remove the three screws holding the aluminum memory cover (right side cover). Release the memory, remove it, and then reinstall it. If it doesn't boot up clean, repeat until it does.
Make sure you are using the latest drivers. If you can't gain access to the Alienware site, try using the Uniwill drivers that can be found here:http://www.uniwill.com/UserDownload/N766S/N766S.php
If you still have problems, let me know and I will do what I can to help.