Try clicking on the ok button (multiple times) until the windows logon screen comes up. If it works and it comes up, please use System Restore to return your computer to an earlier restore point (if your operating system has System Restore). It should be a date just before you watched the dvd.
If you've never done this before, Go to Start / All Programs / Accessories / System Tools / System Restore
check the box to Restore my computer to an earlier time and click on Next. You'll see a calendar with highlighted dates. Choose one of the dates just preceding this problem and allow your system to return to that date. See if the problem goes away.
For Vista: http://www.bleepingcomputer.com/tutorials/...43.html#restore
If this doesn't help and you are still in your computer, please go to Start / Run and copy-paste (or type) in sfc /scannow and click ok.
This will scan your computer and look for corrupt or missing files. If it finds any, it will attempt to find a backup copy on your system or it may ask you to insert your cd.
If you managed to get in and were able to do any of the above and none of it worked, you should go back into system restore using the same steps and undo the change you made.
If you get into your computer, post here and wait for an answer without shutting it back down. If you can't get past the error message to get to the logon screen, then post this information here as well. If any of the above works, please post this as well.