Spot screen my dell vostro 1014 problem that screen spots and when hd video change then screen disturbe

Hello

First find an external monitor to test if its the screen on your laptop or the graphics chip in your laptop. If you have an external monitor then hook it up to your laptop and toggle the video over to see if you still see the spot.If it only shows on the laptop screen the Replace the screen.
Another thing you can do is run the built in Diagnostics
Diagnostics before windows using the F12 Diagnostics
* Reboot and press F12 to enter the Boot Menu
* When the boot device list appears, highlight Diagnostics and press Enter
* The computer begins to run the Pre-boot System Assessment, a series of embedded diagnostics that perform initial testing on your system board, keyboard, hard drive, and display
* If the Pre-boot System Assessment completes successfully, you receive the message Booting Dell Diagnostic Utility Partition
* Press any key to continue
* Press any key to start the Dell Diagnostics from the Diagnostics utility partition on your hard drive
* After the Dell Diagnostics loads and the Main Menu screen appears, click the button for the option you want to run -
Express Test = Performs a quick test of devices. The test typically takes 10 to 20 minutes and requires no interaction on your part
Extended Test = Performs a thorough check of devices. The test typically takes 1 hour or more and requires you to answer questions periodically
Custom Test = Tests a specific device. You can customize the tests to be run
Symptom Tree = Allows you to select tests based on a symptom of the problem you are experiencing
* When you have finished running a test, close the screen to return to the Main Menu screen. To exit the Dell Diagnostics and reboot the computer, close the Main Menu screen.