[FONT="]Method 1:[/FONT] [FONT="]I would suggest you to adjust the screen resolution for your computer display and then check if it still freezes.
[/FONT] [FONT="]To check and adjust the screen resolution for your monitor you may refer to the below provided links and check if these assist you resolve the issue -[/FONT] [FONT="]Getting the best display on your monitor[/FONT] [FONT="]http://windows.microsoft.com/en-US/windows7/Change-your-screen-resolution[/FONT] [FONT="]
[/FONT][FONT="]Method 2:[/FONT] [FONT="]If the issue persists I would suggest you to check for the latest display/video card driver.[/FONT]You may first try uninstall and then reinstalling the display drivers. Then if the issue persists you may check for update of the drivers –
a. Click Start, and then click Control Panel. b. Click System and Maintenance, click System, and then click Device Manager. Note If Control Panel is in Classic View, double-click System, and then click Device Manager.
If you are prompted for an administrator password or for a confirmation, type the password, or click Allow. c. In Device Manager, expand Display Driver, right-click the display devices, and then click properties and under the driver tab click on Uninstall. d. When you are prompted to confirm that you want to remove the device, click OK. e. Restart the computer. After the computer restarts, the drivers will be automatically installed. Check after this procedure. Check after this procedure. Also check if you have any exclamation mark or cross marks alongside the display devices listed in device manager.
To illuminate this, you will have to either manually check the PUS or exchange it with a working one and see if the problem goes away. I would suggest the second option but if you are interested, here's how to manually check the PUS: How to Check Power Supply Wattage | eHow.com