It sounds as if your laptop isn't quite fast enough to keep up with the DVD and whatever else is running in the back ground. Before I'd go with your 2 options that you listed, I'd try to shut down any programs that aren't required at startup.
You can do this by going to Start>Run then type in "msconfig" (without the quotes). A pop up window will open. Click on the "Startup" tab. You'll see a list of programs that start when windows starts (therefore, they run in the background when your computer is on, sucking up valuable computer resources).
Go to the Startup List HERE
on BleepingComputer.com and type in the programs one at a time to see if they're required at startup or not. If it's not listed, then leave it alone! If it is listed, like for example, qttask which is Quick Time, you don't need that to run at startup but it's up to you, well, I'd uncheck the box to the left so that it doesn't run at start up. Also, any auto update features will slow down your machine too, specially if it's got a wireless signal.
Once your done, you'll have to restart your computer. When it restarts, you'll get a warning box saying that you've made changes to your startup. Before you click OK, check the box "don't show this again" (or something to that effect, I believe it's at the bottom of the warning box), then click OK. Try playing a movie now and let's hope that this worked!
EDIT: Added the link for the startup section that I neglected to add in the original post....DOH!
Edited by stevealmighty, 11 January 2007 - 06:14 PM.