You need to open AutoCAD or F/X CAD with the Hardware Acceleration setting disabled.
Some installations require the Hardware Acceleration setting to be disabled for optimum performance. If you've disabled Hardware Acceleration and are now unable to open AutoCAD or F/X CAD, use the steps below to open your installation while Hardware Acceleration is disabled.
1. Right-click the icon for your AutoCAD or F/X CAD installation on your desktop or in the Windows Start menu.
Select the Properties option from the menu that opens.
2. In the Properties dialog box, select the Shortcut tab.
Add a space and the text /nohardware to the end of the entry in the Target field.
Click OK to save the change.
You should now be able to open AutoCAD or F/X CAD successfully.