Hello. I have a three (3) year old Dynabook Tecra A50-F (Toshiba) running Windows 11 Pro with Intel(R) Core(TM) i7-8565U CPU @ 1.80GHz and 16GB of RAM, and when I have it on for a while the screen will go blank while the computer stays on. I thought it was the external monitor that I was using or the HDMI cord, but after disconnecting it and using the laptop monitor, it still happens. It happens when using different programs and if it happens while watching a video (like YouTube) the sound still works fine, but the display goes black. I ran a program to check everything and it says everything is working fine. To fix it, I have to hold down the power for a hard reboot and then it reboots and works fine again. To me it sounds like it could be the graphics card. Any thoughts? Thanks. James.