You need to give us a lot more detail for us to even begin troubleshooting your problem. What you've given us is akin to bringing your car to a repair shop and asking, "My car is making a noise -- what is the definitive cause of this ambiguous noise and exactly how much does it cost to fix it?"
What I'm getting at is that it could be anything from a rock stuck in the brake pads to a complete lack of an engine in the car. The possibilities are too numerous to tell with the lack of information you've offered.
A video of Dreamweaver crashing doesn't help. We believed you when you said it wouldn't launch -- there's no need to prove it.
Give us your Mac details (model, RAM, CPU, etc.). Tell us if you have Adobe CS3 installed alongside CS4 or not. What version of OS X are you running? What do your log files say in the pertinent sections when you tried to launch Dreamweaver? What help is it to say you've "updated all software" when we have no clue what software you're running?
As it stands right now, there could be thousands (or even millions) of different reasons Dreamweaver won't launch, but with the severe lack of information you've given us, any troubleshooting suggestions would be mere shots in the dark. We could suggest things like creating a new user account to see if Dreamweaver behaves under that new account, or to repair permissions on your boot drive, or to boot from your Restore CD/DVD and repair your drive, but those are just catch-all guesses, much like telling a car repairman to simply start replacing parts until the noise stops... that's simply cost-ineffective and a waste of time, and while the repairman will make money off of each part he replaces (at your expense, nonetheless), we do all our troubleshooting for free here -- and time is money here. It would be a waste of time for us to do all the legwork and hand-holding for you -- do some research, post some logs, do SOMEthing to help us along in our free troubleshooting endeavors.
Here's a tip: help us help you. You cannot possibly give us too much information, but you can give us pathetically too little information to try and help you (which is what you've done).
Elaborate. Greatly. Please.