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I understand that when launching AutoCAD 2012, it shows the error "Heidi Module Load Error. The configured Heidi driver cannot be loaded. Switching to default software driver."
Heidi errors like this have to do with the video driver on your system. Often simply uninstalling and reinstalling the video driver will fix the problem. Aside from getting the current driver from the manufacturer's web site, you can also check your video card and driver against those that we have tested and certified:
Sometimes the latest video driver available from the manufacturer is not the latest one that we have tested. For the reinstall process, I would recommend uninstalling your current video driver, reboot, install the driver again (or an updated version), and reboot once more.
Another cause of the Heidi error could be your printer driver. Try changing the default printer driver on your system and then launch AutoCAD to see if the error occurs.
If reinstalling the video driver or changing the default printer does not fix the problem and if you can get into AutoCAD and enter the 3DCONFIG command, hit the Manual Tune button in the window that comes up and then turn off Enable Hardware Acceleration. If you cannot get into AutoCAD, try turning off video hardware acceleration in the Windows display settings or add a /nohardware switch to the AutoCAD shortcut. Here is an article about using the /nohardware switch:
Please let me know if this resolves the issue.
Autodesk Support Team